Table of Contents
Overview
Definition of Embryology
Embryology is the branch of biology that studies the formation and development of embryos and fetuses, encompassing the entire process from fertilization to birth. This field highlights the complexity and delicacy of prenatal development, which significantly impacts the future health and wellbeing of the child.[2.1] Embryology is divided into three distinct periods: the germinal, embryonic, and fetal periods. The germinal period, or pre-embryonic stage, lasts approximately 14 days from conception until the zygote implants in the uterine lining. During this stage, cell division occurs without significant growth, resulting in a cluster of cells that remains the same size as the original zygote.[4.1] The embryonic period follows, spanning from the third to the eighth week of development, and the fetal period extends from the ninth week until birth.[1.1] Historically, embryology has been studied for thousands of years, with early investigations evident in ancient cultures, such as Ancient Egypt, where observations were made through the examination of miscarriages and fetuses.[6.1] The term "embryology" is derived from the Greek words for "the unborn" and "study," reflecting its focus on the early stages of life.[7.1] Aristotle made significant contributions to the field, providing extensive writings and influencing subsequent discussions through his comparative methods and classifications of embryonic development.[7.1]Importance of Embryology
Embryology is a critical field that provides essential knowledge for developing effective health care strategies aimed at improving reproductive outcomes. A comprehensive understanding of embryology facilitates the creation of new techniques for prenatal diagnosis and treatment, therapeutic procedures to address infertility, and mechanisms to prevent birth defects, which are a leading cause of infant mortality.[13.1] The embryonic period, which begins at fertilization and lasts approximately eight weeks, is a crucial phase of fetal development. During this time, various factors, including maternal health, nutrition, lifestyle, and environmental exposure, significantly influence fetal growth and development.[15.1] Maternal nutrition, in particular, plays a vital role in ensuring optimal fetal development, as suboptimal nutrition during gestation can lead to significant health issues across various animal species, including humans.[16.1] Embryology is a critical field that explores the intricate processes of early embryonic development, beginning with a single fertilized egg. This initial stage involves several rounds of division, leading to the formation of a blastocyst, which signifies a pivotal transition from a free-floating embryo to one that establishes contact with the maternal endometrium.[22.1] During this process, the zygote undergoes the maternal-to-zygotic transition, allowing it to gain control over its own development. This transition is essential as it involves key cell fate decisions that result in the differentiation into an embryonic lineage and two extra-embryonic lineages.[22.1] The cellular processes that occur during these early stages are foundational for the overall health and functionality of the organism later in life, as they set the groundwork for complex organismal development.[24.1] Understanding these processes is vital for advancing prenatal care and ensuring the well-being of both the mother and the developing fetus.[24.1] Advancements in embryological research, particularly in genetic manipulation, raise significant ethical issues, including concerns about designer babies and the long-term effects on the human gene pool. The ethical dimensions of genetic modification are particularly pronounced in discussions surrounding human germline editing, as changes made in the germline can be passed down to future generations.[21.1] The debate about genome editing has gained renewed attention with the advent of CRISPR technology, which offers more accurate and accessible editing capabilities compared to older methods.[21.1] As of 2014, approximately 40 countries have discouraged or banned research on germline editing due to ethical and safety concerns, highlighting the need for stringent regulations and oversight.[21.1] The International Summit on Human Gene Editing emphasized the necessity of ongoing global engagement and discussion, advocating for intensive basic and preclinical research under appropriate legal and ethical frameworks.[20.1] Researchers and ethicists generally agree that until germline genome editing is deemed safe, it should not be utilized for clinical reproductive purposes, as the risks cannot be justified by potential benefits.[21.1] Furthermore, there are concerns regarding the equitable access to these technologies, as genome editing may only be accessible to the wealthy, exacerbating existing disparities in healthcare.[21.1]History
Early Theories and Discoveries
The study of embryology has its roots in ancient philosophical inquiries, with Aristotle (384-322 BCE) being a pivotal figure in its early development. Aristotle's extensive observations of animal development, particularly his meticulous studies of chick embryos, laid foundational principles for understanding embryonic growth. He articulated a theory of epigenesis, positing that organisms develop through a series of stages before reaching their final form, a concept that dominated embryological thought for over 1500 years.[56.1] His work, particularly in "On the Generation of Animals," introduced methods of investigation and reasoning that influenced subsequent thinkers in the field.[56.1] Following Aristotle, significant advancements occurred during the Renaissance and Enlightenment periods. The seventeenth century saw the emergence of William Harvey (1578-1657), who challenged existing notions of embryonic development. Harvey's investigations raised doubts about Aristotle's theories and contributed to a shift in understanding the processes of fertilization and early development.[57.1] This period marked a transition from philosophical speculation to empirical observation, as scientists began to utilize more rigorous methodologies in their studies. Joseph Needham's "A History of Embryology," published in 1959, highlights the significant advancements in embryology from 1600 to 1800, a period marked by a remarkable amount of scientific work in the field.[47.1] In his examination, Needham discusses the contributions of key figures such as William Harvey, who is noted for his studies on chick and fish embryos, which helped to re-establish embryology as an observational science.[51.1] Additionally, the nineteenth century saw transformative developments, including the establishment of experimental embryology by Wilhelm Roux and Hans Driesch, alongside the discovery of the mammalian ovum by Karl Ernst von Baer.[50.1] These advancements shifted the discourse from philosophical debates to a more empirical understanding of embryological development, reflecting a significant evolution in the field.[50.1]Modern Embryology Development
Modern embryology has undergone significant transformation since the advent of assisted reproductive technologies (ART) in the late 20th century. The birth of Louise Brown in 1978, recognized as the world's first test tube baby, marked a pivotal moment that not only brought joy to many couples facing infertility but also ignited extensive ethical, legal, and social debates surrounding reproductive technologies.[71.1] These technologies, including in vitro fertilization (IVF) and genetic testing, have raised profound ethical considerations that challenge existing societal norms and medical ethics.[70.1] As ethical issues in reproductive technologies continue to emerge, they represent a significant subset of obstetric ethics, where the concept of the fetus as a patient is central. This concept must be integrated into our ethical framework, emphasizing that the moral status of the fetus should not be determined solely by independent features of the fetus.[66.1] In this rapidly evolving field, there is a pressing need for a robust ethical framework to guide both clinical practice and research.[68.1] Furthermore, the ethical considerations surrounding new reproductive technologies have been articulated by the Ethics Committee of the American Fertility Society, which underscores the importance of respecting human life and the dignity of procreation.[69.1] The integration of modern technologies, particularly CRISPR/Cas9 and advanced imaging techniques, has significantly transformed our understanding of embryological processes. Recent research has demonstrated the application of CRISPR/Cas9 technology to correct a pathogenic MYBPC3 mutation in human preimplantation embryos through homology-directed repair, addressing a mutation that leads to hypertrophic cardiomyopathy, a common cause of sudden cardiac death.[72.1] Concurrently, imaging techniques have rapidly evolved, transitioning from two-dimensional to high-resolution three-dimensional (3D) ultrasound, which has enhanced the visualization of small embryos and fetuses.[76.1] Innovative techniques like HDlive generate near-realistic images of the human fetus, allowing for the definition of in-vivo anatomy, including the visualization of embryonic circulation and dynamic features that were previously unattainable.[76.1] Furthermore, these advancements contribute to ongoing philosophical debates regarding the autonomy of pregnant mothers and the personhood status of the human zygote, embryo, and fetus, as several philosophers have developed "personhood criteria" that pertain to human capabilities, physical development, and psychosocial and reasoning capacities.[79.1] The ethical challenges associated with embryo research are complex and significant. A central issue in these discussions is the belief held by some that life begins at conception, which leads to objections against research that utilizes or destroys human embryos.[78.1] This perspective raises important ethical questions regarding the moral status of embryos, particularly in the context of advancements in embryological research, including studies on embryonic stem cells and early human development. The ‘natural’ embryo, formed by the fertilization of an egg cell, is often considered the gold standard in this research. However, the criteria for determining when the relevant developmental potential cannot be reasonably excluded may influence current research involving integrated embryo-like structures (ELSs). If integrated ELSs are morphologically and molecularly indistinguishable from natural human embryos, they may be regarded as morally equivalent, which has implications for the ethical landscape of embryo research.[77.1] Additionally, ethical concerns arise regarding the sources of embryos, particularly in relation to informed consent and the potential risks faced by egg donors when embryos are specifically created for research purposes.[78.1] These ongoing debates necessitate a careful examination of the implications of contemporary reproductive technologies on human life and dignity.Developmental Stages
Embryonic Stage
The embryonic stage of development occurs from the third to the eighth week after conception, following the germinal period, which encompasses the first two weeks. This stage is critical as it involves significant cellular processes such as cell division, migration, and differentiation, which lay the foundation for the formation of major organs and systems in the developing organism.[89.1] The embryonic stage of development commences with fertilization, a highly regulated process in which a sperm and an egg fuse to form a zygote.[102.1] This zygote, a single-celled entity, undergoes rapid cell divisions known as cleavage, resulting in the formation of a blastula.[103.1] Initially, the zygote divides to form two blastomeres, which continue to divide, eventually leading to the morula stage.[104.1] The cleavage process is characterized by multiple rounds of cell division with a unique embryonic cell cycle that lacks G1 and G2 phases, resulting in a reduction of cytoplasmic volume in each daughter cell.[104.1] Following the cleavage stage, the blastula undergoes gastrulation, a critical process that establishes three germ layers: ectoderm, mesoderm, and endoderm, which will later differentiate into specific tissues and organs.[102.1] During the first 8-12 weeks of human gestation, the early embryo develops in a tightly controlled and relatively protected environment. During this period, the delivery of maternal blood and oxygen to the developing embryo is limited, and essential nutrients are supplied through the decidual uterine glands, the placental trophoblast, and the secondary yolk sac.[111.1] The embryo is highly sensitive to various environmental factors, including temperature, air quality, and light exposure, which can significantly impact its development.[110.1] Adverse environmental conditions can lead to negative outcomes, such as embryonic death, primarily due to chromosomal abnormalities that disrupt normal developmental processes.[113.1] Furthermore, changes in environmental conditions can cause the embryo to optimize its future development program, resulting in a form of plasticity related to predictive adaptive responses.[112.1] The embryonic stage is also characterized by the organogenic period, where the foundations for all major organ systems are established. This period is crucial for the embryo's development, as it is during these weeks that teratogens can have severe effects, potentially leading to developmental anomalies.[88.1] Thus, the embryonic stage is a vital phase in the overall development of a human being, setting the stage for the subsequent fetal period, which begins at the ninth week of gestation.[89.1]Medical Applications
Reproductive Medicine
Embryology holds significant implications for reproductive medicine, as it is essential for diagnosing and treating various reproductive disorders, including miscarriage, stillbirth, and birth defects.[133.1] By integrating newer molecular medical embryology with traditional approaches to developmental anatomy, embryology has become a vital component of the standard medical curriculum, enhancing our understanding of human life and prenatal development.[134.1] This integration not only enriches the educational framework but also provides critical insights that inform clinical practices in reproductive health. The integration of molecular medical embryology with traditional developmental anatomy has established embryology as a vital component of the standard medical curriculum.[134.1] This field not only has theoretical significance as a pre-clinical course during medical education but also holds important clinical relevance.[135.1] Embryology plays a crucial role in understanding human life and prenatal development, offering valuable insights that are essential for future healthcare professionals.[134.1] Furthermore, it serves as an essential tool in clinical practice, particularly for managing various medical disorders related to reproduction.[136.1] Despite its importance, teaching embryology within the 21st-century medical curriculum presents challenges, making it a complex subject to understand and convey effectively.[136.1] Advancements in embryology have significantly impacted assisted reproductive technologies (ART), particularly in in vitro fertilization (IVF). A comprehensive understanding of embryonic development is crucial, as it informs the evaluation and selection of embryos, which is essential for achieving successful IVF outcomes. The process of embryo evaluation aims to identify the most viable embryos from a larger cohort of fertilized oocytes, many of which may not develop normally due to chromosomal imbalances or other factors.[147.1] It is widely recognized that the quality of oocytes and embryos plays a vital role in the success of IVF, leading to the establishment of various criteria for assessing their quality, primarily based on morphological characteristics. These criteria are designed to select high-quality oocytes and embryos, thereby improving the chances of subsequent pregnancies.[148.1] Recent innovations in embryo culture techniques and genetic screening have further refined ART, increasing success rates and expanding options for couples facing infertility.[155.1] For instance, the incorporation of microfluidics technology into IVF laboratories has enhanced embryo manipulation and culture conditions, potentially reducing the need for invasive procedures like Intracytoplasmic Sperm Injection (ICSI).[153.1] Additionally, noninvasive preimplantation genetic testing (PGT) utilizing cell-free DNA from embryo culture media represents a significant advancement in the field, allowing for better selection of embryos prior to implantation.[153.1]Teratology and Congenital Disorders
Recent advancements in molecular techniques have significantly enhanced our understanding of teratology and congenital disorders, particularly through the application of single-cell and spatial omic technologies. These tools have emerged as powerful means to unravel the complexities of cellular organization and gene expression dynamics during tissue development, which are critical for identifying and addressing developmental disorders.[143.1] Moreover, the establishment of human pluripotent stem cell (PSC) lines that represent early human embryo lineages has facilitated the modeling of both human and non-human primate embryos. This progress allows researchers to guide PSCs into various embryonic and extra-embryonic cell types, thereby providing insights into the mechanisms underlying congenital disorders.[144.1] Innovative approaches, such as those developed by scientists at UC Santa Cruz, have enabled the engineering of cellular models that mimic the early stages of embryonic development without the need for actual embryos. By utilizing CRISPR-based methods, researchers can prompt stem cells to form "programmable" embryo-like structures, or embryoids, which replicate the organization and gene activation patterns observed in living organisms. This capability allows for the investigation of specific genes' roles in early development and their potential links to congenital disorders.[145.1] Additionally, initiatives like the 'Deciphering the Mechanisms of Developmental Disorders' (DMDD) programme aim to systematically identify embryonic lethal knockout lines in the UK over the next five years. This program employs comprehensive imaging and transcriptomics to detect abnormalities in embryo structure and development, further contributing to the understanding of teratology and congenital disorders.[146.1]In this section:
Recent Advancements
Genetic Engineering and Embryo Editing
Recent advancements in embryology have significantly influenced the fields of genetic engineering and embryo editing. A pivotal breakthrough in this area is the generation of synthetic embryos using stem cells, which provides a more accurate model of early human development. These synthetic embryos, created without the use of eggs or sperm, allow researchers to study the earliest stages of human life and may offer ethical alternatives to traditional in vitro fertilization (IVF) methods.[182.1] The development of synthetic human embryos presents significant ethical challenges concerning their moral status, use, and regulation.[179.1] These ethical dilemmas are particularly pronounced when compared to traditional reproductive technologies, which often involve the destruction of embryos. The potential utilization of synthetic embryos in human reproduction is likely to provoke much more moral outrage and ethical controversy than their applications in non-reproductive biomedical contexts.[181.1] Advancements in artificial intelligence (AI) are significantly transforming the field of assisted reproductive technology (ART), particularly in the selection and prediction of viable embryos. AI methods are being integrated into various aspects of reproductive medicine, enhancing the selection of sperm cells, oocytes, and embryos, and generating better predictive models for in vitro fertilization (IVF).[188.1] This integration of AI holds the potential to improve success rates and alleviate the emotional and financial burdens associated with infertility.[186.1] However, the use of AI in this sensitive area also raises important ethical considerations, particularly regarding patient autonomy and the potential for biased decision-making based on algorithmic models.[189.1] For instance, models for embryo selection may inadvertently favor certain traits perceived to correlate with implantation success, which could conflict with patients' values, such as preferences for random sex selection.[189.1] Engaging stakeholders, especially from underrepresented communities, is essential in shaping ethical AI practices in reproductive health.[184.1] As the field continues to evolve, the intersection of genetic engineering, embryo editing, and AI in reproductive medicine presents both exciting possibilities and significant ethical challenges that must be carefully navigated.Stem Cell Research and Applications
Recent advancements in stem cell research, particularly the use of adipose-derived stem cells (ADSCs), have shown promise in the treatment of male infertility due to their pluripotent nature, which allows them to differentiate into any cell type of the three germ layers.[174.1] The integration of microfluidics technology into in vitro fertilization (IVF) laboratories has introduced several advantages, including precisely controlled fluidic manipulations of gametes and embryos, the provision of biomimetic culture environments, and enhanced automation.[176.1] These innovations have contributed to a steady improvement in global IVF success rates, which have risen by 5-10% since 2023, largely attributed to technological innovations and refined treatment protocols.[178.1] In addition to these advancements, the development of synthetic embryos from stem cells has provided valuable insights into early developmental processes. These synthetic models, while not true embryos, closely mimic key aspects of embryonic development, allowing researchers to study genetic and environmental influences on embryonic formation.[192.1] Notably, studies have shown that these models can replicate transcriptional trajectories similar to those of natural embryos, highlighting their potential for advancing our understanding of developmental disorders.[190.1] However, ethical and regulatory challenges remain a significant concern in research involving human embryos, necessitating careful consideration in the application of these technologies.[193.1] Recent advancements in embryo viability assessment have introduced a range of new non-invasive tests designed to measure specific molecules in the culture medium, such as amino acids and proteins, to determine the metabolic activity of embryos.[197.1] These tests aim to enhance the selection process for viable embryos by providing insights into what the embryo has utilized or secreted during development. Additionally, embryo grading remains a critical method for assessing embryo health and developmental potential, focusing on various visual indicators that correlate with successful development.[194.1] Notably, embryos transferred on the fifth day of development, as blastocysts, are generally considered superior to those transferred on Day 3 due to higher pregnancy rates and better embryo selection, which allows for a more thorough evaluation of embryo quality.[196.1] Collectively, these innovations in stem cell research and applications are significantly transforming the field of embryology, paving the way for improved reproductive health outcomes.In this section:
Ethical Considerations
Ethical Implications of Embryo Editing
Research involving human embryos, particularly embryo editing, raises significant ethical implications that are influenced by various philosophical perspectives on the moral status of the embryo. The moral status of the human embryo is central to contemporary debates on cloning, embryo research, stem cell research, genetic engineering, assisted reproduction, and other related fields.[227.1] This status has been legally recognized and defined in the 1990 Human Fertilisation and Embryology Act, which permits embryo freezing, experimentation, and disposal up to 14 days after fertilization, reflecting a lowered status for the human embryo.[225.1] The ethical, moral, and legal status of the embryo has sparked passionate debate, with some arguing that the moral status of the embryo is tied to the concept of personhood, which distinguishes humans from non-human animals.[228.1] These differing philosophical viewpoints contribute to the ongoing discourse regarding the protection and moral consideration afforded to embryos in various scientific and medical contexts. The ethical implications of embryo editing are significantly shaped by the legal framework established by the Human Fertilisation and Embryology Act of 1990, which permits the freezing, experimentation, and disposal of human embryos up to 14 days post-fertilization.[225.1] This legal definition has profound ramifications for the ethical landscape, as it delineates the boundaries of permissible research activities. However, the emergence of embryo-like structures, or embryoids, created from pluripotent stem cells, challenges these existing legal definitions and raises critical questions regarding their moral status.[224.1] The use of these models necessitates a reconsideration of the full ban on embryo research beyond the 14-day rule, advocating for a sliding scale that reflects the completeness of the model.[224.1] Furthermore, the discussion surrounding embryo models underscores the need for a refined legal definition of an embryo and the identification of "tipping points" at which these structures may be regarded as embryos.[213.1] As such, addressing the complexities introduced by these new scientific advancements requires a careful reevaluation of both legal definitions and ethical considerations surrounding embryo editing.[213.1] The ethical discourse is further complicated by the potential benefits of embryo editing, which could lead to significant advancements in human health and reproduction.[214.1] Proponents argue that research involving embryos is ethically acceptable if it is likely to yield substantial new knowledge that benefits human well-being.[212.1] However, the moral implications of manipulating embryos, particularly regarding their potential to develop into human life, necessitate careful consideration of the ethical boundaries that should govern such research.[227.1]Future Directions
Emerging Technologies in Embryology
Recent advancements in embryology have been significantly influenced by emerging technologies, particularly in the realm of synthetic embryos and artificial intelligence. The development of synthetic embryos, created from stem cells without the need for fertilization, represents a groundbreaking shift in the study of early human development. These synthetic models have been shown to replicate many features of natural embryos, providing researchers with valuable insights into embryonic development and potential applications in regenerative medicine and the understanding of congenital disorders.[264.1] In addition to synthetic embryos, the integration of artificial intelligence (AI) into embryology is transforming fertility treatments and patient outcomes. AI technologies are being utilized to enhance embryo assessment processes, which have traditionally relied on visual evaluations. By employing deep learning algorithms, researchers aim to improve the accuracy and efficiency of embryo selection during in vitro fertilization (IVF) procedures.[266.1] This technological integration not only streamlines the assessment process but also holds the potential to increase the success rates of fertility treatments. Furthermore, the exploration of advanced embryo models is enhancing our understanding of gene regulation and tissue organization during early development. Studies have demonstrated that fine-tuning developmental pathways can induce embryonic structure formation in controlled environments, thereby offering new avenues for research into early human life.[256.1] The implications of these advancements extend beyond basic science, as they may lead to significant societal consequences in regenerative and reproductive medicine over the next decade.[253.1] As the field progresses, ethical considerations surrounding the use of synthetic embryos and AI in embryology will be paramount. The establishment of ethical guidelines by organizations such as the International Society for Stem Cell Research underscores the need for responsible research practices that maintain public trust while exploring the potential of these innovative technologies.[262.1]Potential Impacts on Human Health
Advancements in embryology, particularly through technologies such as CRISPR-driven stem cell engineering and 3D bioprinting, are poised to significantly transform human health. These innovations are paving the way for personalized regenerative therapies, which offer hope for patients suffering from various conditions, including age-related diseases and injuries.[273.1] The integration of 3D bioprinting is particularly noteworthy, as it allows for the fabrication of complex biological structures with high precision, which is essential for tissue engineering and regenerative medicine.[274.1] This technology enables the creation of patient-specific scaffolds that can mimic the spatial geometry and microstructures of natural tissues, thereby enhancing the effectiveness of therapeutic applications.[275.1] However, the clinical application of stem cell therapies raises numerous ethical and safety concerns that must be addressed. The ethical implications of stem cell research encompass a range of issues, including risks, side effects, and the therapeutic value of such interventions.[286.1] As stem cell therapy continues to evolve, it is crucial to consider the broader ethical landscape, which includes the potential for human cloning and the creation of human-animal chimeras through the unlimited differentiation potential of induced pluripotent stem cells (iPSCs).[289.1] These ethical dilemmas highlight the need for robust frameworks to guide the responsible application of these technologies in clinical settings. Despite these challenges, stem cell therapy remains a promising avenue for treating age-related neurodegenerative diseases and stroke, with ongoing research aimed at optimizing delivery protocols to ensure safety and efficacy in older populations.[291.1] As the field progresses, it is essential for researchers to remain cognizant of the population-level implications of stem cell therapies and their potential impact on society.[290.1] The future of embryology, therefore, not only holds the promise of revolutionary health interventions but also necessitates careful consideration of the ethical frameworks that will govern their application.References
[1] Basics of embryology - Knowledge - AMBOSS — Embryology is the study of the origin and prenatal development of an organism, comprising the germinal (first two weeks from conception), embryonic (third to eighth week from conception), and fetal period (ninth week from conception until birth). Gestation in embryology refers to conceptional age, i.e., the time period from conception to birth, and should be distinguished from gestational age
[2] 1. The Basics of Embryology - SimpleMed - Learning Medicine, Simplified — Embryology is the study of the development of the embryo and the journey from fertilisation of the egg to the formation of a baby. This is an amazingly complex and delicate process which has impacts on the future health and wellbeing of a child. ... Summary of Week 3. Gastrulation begins and the primitive streak forms. Epiblast differentiates
[4] 24.1: Overview of Embryology and Fetal Development — Pre-embryonic Stage. The pre-embryonic, or germinal, period, about 14 days in length, is the shortest stage and lasts from conception to implantation of the zygote (fertilized egg) in the lining of the uterus.During this stage cell division with no significant growth produces a cluster of small cells that is the same size as the original zygote.
[6] History of embryology - Wikipedia — Embryology is the study of the stages of prenatal development.The history of embryology goes back thousands of years, and prenatal biology was already being studied in the cultures with the earliest written records. In Ancient Egypt, information on prenatal development was learned by looking at miscarriages and fetuses from embalmed pregnant women through several stages of the pregnancy.
[7] Embryology - Wikipedia — Embryology (from Greek ἔμβρυον, embryon, "the unborn, embryo"; and -λογία, -logia) is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Means by which we know Aristotle studied embryology, and most likely his predecessors as well, was through studying developing embryos taken out from animals as well as aborted and miscarried human embryos. Aristotle singularly wrote more on embryology than any other pre-modern author, and his influence on the subsequent discussion on the subject for many centuries was immense, introducing into the subject forms of classification, a comparative method from various animals, discussion of the development of sexual characteristics, compared the development of the embryo to mechanistic processes, and so forth.
[13] Embryology- History, Theory, Fields, Scope, Careers, Uses - Microbe Notes — Provide knowledge essential for creating health care strategies for better reproductive outcomes; A better understanding of embryology results in new techniques for prenatal diagnoses and treatments, therapeutic procedures to circumvent problems with infertility, and mechanisms to prevent birth defects, the leading cause of infant mortality.
[15] Understanding Fetal Development: What You Need To Know — The first stage of fetal development is the embryonic period, which begins at fertilization and lasts for about 8 weeks. ... There are several key factors that can affect fetal development, including maternal health, nutrition, lifestyle, and environmental exposure. ... monitoring fetal development is a critical aspect of prenatal care that
[16] Maternal Nutrition and Fetal Development - The Journal of Nutrition — Maternal nutrition plays a critical role in fetal growth and development. Although considerable effort has been directed towards defining nutrient requirements of animals over the past 30 y, suboptimal nutrition during gestation remains a significant problem for many animal species (e.g., cattle, pigs, and sheep) worldwide ().Despite advanced prenatal care for mothers and fetuses, ∼5% of
[20] Ethical considerations of gene editing and genetic selection — At the end of the summit, the organizing committee released a statement advising ongoing global engagement and discussion, and outlined their conclusions regarding gene editing: 97 “(i)ntensive basic and preclinical research is clearly needed and should proceed, subject to appropriate legal and ethical rules and oversight…”; “(m)any promising and valuable clinical applications of gene editing are directed at altering genetic sequences only in somatic cells… [and] they can be… evaluated within existing and evolving regulatory frameworks for gene therapy…”; and “(g)ene editing might also be used, in principle, to make genetic alterations in gametes or embryos…” The statement goes on to address the ethical, legal, and scientific questions surrounding germline editing that have yet to be answered, and warns: Tang L, Zeng Y, Du H, Gong M, Peng J, Zhang B, et al CRISPR/Cas9‐mediated gene editing in human zygotes using Cas9 protein.
[21] What are the Ethical Concerns of Genome Editing? — Most of the ethical discussions related to genome editing center around human germline because editing changes made in the germline would be passed down to future generations. Overview The debate about genome editing is not a new one but has regained attention following the discovery that CRISPR has the potential to make such editing more accurate and even "easy" in comparison to older technologies. As of 2014, there were about 40 countries that discouraged or banned research on germline editing, including 15 nations in Western Europe, because of ethical and safety concerns.3 There is also an international effort led by the US, UK, and China to harmonize regulation of the application of genome editing technologies. Researchers and ethicists who have written and spoken about genome editing, such as those present at the International Summit on Human Gene Editing, generally agree that until germline genome editing is deemed safe through research, it should not be used for clinical reproductive purposes; the risk cannot be justified by the potential benefit. Researchers and bioethicists also worry about the possibility of obtaining truly informed consent from prospective parents as long as the risks of germline therapy are unknown.10 Justice and Equity As with many new technologies, there is concern that genome editing will only be accessible to the wealthy and will increase existing disparities in access to health care and other interventions.
[22] The physiological and pathological mechanisms of early embryonic ... — Abstract. Early embryonic development is a complex process. The zygote undergoes several rounds of division to form a blastocyst, and during this process, the zygote undergoes the maternal-to-zygotic transition to gain control of embryonic development and makes two cell fate decisions to differentiate into an embryonic and two extra-embryonic lineages.
[24] Blastocyst Development and Implantation Stages - BiologyInsights — The journey from a single fertilized egg to a complex organism begins with the early stages of embryonic development, where precise cellular processes set the foundation for life. Understanding blastocyst development and implantation marks the transition from a free-floating embryo to one that establishes contact with the maternal endometrium
[47] Images, science, and rights of the early modern fetus - PMC — THE SCIENCE Joseph Needham in the 1959 edition of his book, The History of Embryology, noted the extraordinary amount of work being accomplished in the science of embryology from the period of 1600 to 1800. 10 Until this period, the pedagogy of procreation had been dictated by the ancients.
[50] Embryology - History Of Embryology As A Science - JRank — During the nineteenth century, cell theory, the discovery of the mammalian ovum by Karl Ernst von Baer (1792-1876), and the establishment of experimental embryology by Wilhelm Roux (1850-1924) and Hans Driesch (1867-1941) transformed philosophical arguments about the nature of embryological development.
[51] A History of Embryology (1959), by Joseph Needham — A History of Embryology (1959), by Joseph Needham | Embryo Project Encyclopedia A History of Embryology (1959), by Joseph Needham A History of Embryology, by Joseph Needham Needham argues that Aristotle may have even observed a human embryo–an extraordinary feat for a scientist at the time given that aborted embryos were not that easy to come by. Albert also studied chick and fish embryos and wrote extensively about each organism’s development, helping to bring embryology back into the observational and scientific realm. In chapter three Needham examines embryology in the seventeenth century and introduces the embryology-related work of William Harvey (1578 AD–1667 AD). In the last chapter of A History of Embryology Needham describes how eighteenth century embryologists continued to be befuddled about fetal nutrition. Wellner, Karen, "A History of Embryology (1959), by Joseph Needham".
[56] Aristotle (384-322 BCE) | Embryo Project Encyclopedia — In natural philosophy, later called natural science, Aristotle established methods for investigation and reasoning and provided a theory on how embryos generate and develop. Aristotle discussed the four causes is in Physics II 3, and the application of his theory of causation to the study of living forms is found in Book I of The Parts of Animals. Through his study of chick embryos, Aristotle articulated principles of generation to account for the theory that developing organisms go through a series of stages before acquiring their final form, a theory later called epigenesis. "Science and Philosophy in Aristotle's Generation of Animals." Journal of the History of Biology 3 (1979): 1–52. Greece development philosophy Plato Physics Natural history Embryology Epigenesis Marine Organisms Biology Embryonic Development Aristotle
[57] Embryology - History of embryology as a science - Development, Human ... — Aristotle's theory of epigenetic development dominated the science of embryology until the work of physiologist William Harvey (1578-1657) raised doubts about A human two-cell embryo 24 hours after fertilization.
[66] Ethical considerations in newer reproductive technologies — Ethical issues in reproductive technologies are a subset of obstetric ethics in which the concept of the fetus as a patient plays a central role. 1 This concept therefore needs to be part of our ethical framework. The concept of the fetus as a patient should not be understood on the basis of the independent moral status of the fetus, ie, some feature(s) of the fetus that, independently of
[68] Ethical considerations in newer reproductive technologies — Ethics is an essential dimension of newer reproductive technologies. In this rapidly evolving field, there is a need for an ethical framework to guide both clinical practice and research. ... Ethical considerations in newer reproductive technologies Semin Perinatol. 2003 Dec;27(6):427-34. doi: 10.1053/j.semperi.2003.10.002.
[69] 7 New Technologies: The Ethical and Social Issues - National Center for ... — Ethical considerations of the new reproductive technologies. By the Ethics Committee (1986-7) of the American Fertility Society, in light of Instruction on the Respect for Human Life in Its Origin and on the Dignity of Procreation, issued by the Congregation for the Doctrine of the Faith. Vol. 49, Supplement 1. [PubMed: 3276566]
[70] The Ethical, Legal, and Social Issues Impacted by Modern Assisted ... — Abstract. Background.While assisted reproductive technology (ART), including in vitro fertilization has given hope to millions of couples suffering from infertility, it has also introduced countless ethical, legal, and social challenges. The objective of this paper is to identify the aspects of ART that are most relevant to present-day society and discuss the multiple ethical, legal, and
[71] Assisted reproduction: Ethical and legal issues - ScienceDirect — The landscape of reproductive health was forever changed in 1978 after the birth of Louise Brown, 'the world's first test tube baby' .The introduction of in-vitro fertilization (IVF) - with its ability to segment and modify what in the past had been a rather obscure biological process - brought as much social, ethical, and legal controversy as it did happiness and meaning to the
[72] Gene Editing of Human Embryos with CRISPR/Cas9: Great Promise Coupled ... — Ma et al. 1 recently described the use of CRISPR/Cas9 technology to correct a pathogenic mutation in human embryos. The authors corrected a heterozygous MYBPC3 mutation in human preimplantation embryos through homology-directed repair. This autosomal dominant mutation leads to hypertrophic cardiomyopathy, which is a common cause of sudden
[76] Neurosonoembryology by three-dimensional ultrasound — High-resolution three-dimensional (3D) ultrasound has enabled the visualization of small embryos and fetuses, and embryology in vivo - '3D sonoembryology' - has been established based on conventional embryology. Recently developed imaging techniques allow the definition of in-vivo anatomy including visualization of the embryonic circulation and dynamic features that could not be
[77] Ethical considerations on the moral status of the embryo and embryo ... — In embryo research (including basic research into early human development, embryonic stem cell research, and applied research in the context of reproductive medicine), the ‘natural’ embryo, formed by the fertilization of an egg cell, remains the gold standard. However, the criteria for when the relevant developmental potential cannot be reasonably excluded may affect the present research with integrated ELSs. If being morphologically and molecularly indistinguishable is sufficient for this, current research on integrated ELSs should perhaps already be regarded as morally equivalent to research using natural human embryos (Health Council of the Netherlands 2023). As a consequence, non-integrated ELSs should be used in research, whenever reliable and efficient, given their lower moral status compared to integrated ELS or natural embryos.
[78] Transparency in controversial research: A review of human embryo ... — This research presents several ethical challenges. Some view life as starting at conception and thus object to research that uses or destroys human embryos (George and Tollefsen, 2023; Matthews et al., 2021a, 2021b).Additional concerns include the sources of the embryos, particularly as they relate to informed consent, potential risks to egg donors when embryos are created specifically for
[79] Personhood status of the human zygote, embryo, fetus - PMC — These findings are a factor in the debate regarding the autonomy of pregnant mothers and personhood status of the human zygote, embryo, and fetus. Thesis. Several philosophers have developed "personhood criteria" that pertain to human capabilities, physical development, and psychosocial and reasoning capacities.
[88] Stages of Embryo Development: Understanding the Journey of Life — The early stages of embryo development are essential for laying the groundwork for the later stages of fetal development, which ensure the formation of all major organs and systems. ... Once the embryo implants into the uterine lining, it begins the next phase of development—becoming a fetus. Key milestones include: Week 2: Formation of the
[89] 28.2 Embryonic Development - Anatomy & Physiology — The period of time required for full development of a fetus in utero is referred to as gestation (gestare = “to carry” or “to bear”). A developing human is referred to as an embryo during weeks 3–8, and a fetus from the ninth week of gestation until birth. In this section, we’ll cover the pre-embryonic and embryonic stages of development, which are characterized by cell division, migration, and differentiation. Some grow to form the extra-embryonic membranes needed to support and protect the growing embryo: the amnion, the yolk sac, the allantois, and the chorion. Each of these germ layers will develop into specific structures in the embryo.
[102] 5.5 Fertilization and Early Embryonic Development — Fertilization, pictured in Figure 1a is the process in which gametes (an egg and sperm) fuse to form a zygote. (a) Fertilization is the process in which sperm and egg fuse to form a zygote. The development of multi-cellular organisms begins from a single-celled zygote, which undergoes rapid cell division to form the blastula. Mammals at this stage form a structure called the blastocyst, characterized by an inner cell mass that is distinct from the surrounding blastula, shown in Figure 2b. The blastula, which in some species is a hollow ball of cells, undergoes a process called gastrulation, in which the three germ layers form.
[103] 24.6. Fertilization and Early Embryonic Development — The development of multi-cellular organisms begins from a single-celled zygote, which undergoes rapid cell division to form the blastula. The rapid, multiple rounds of cell division are termed cleavage. Cleavage is illustrated in (Figure 24.24 a). After the cleavage has produced over 100 cells, the embryo is called a blastula.
[104] BGDA Practical 3 - Early Cell Division - Embryology — First cell divisions of the zygote forming initially 2 blastomeres and continuing to divide to form the morula. This early mitosis is a unique embryonic cell cycle (M, S, M phases) compared to adult (M, G 1, S, G 2, M phase). With virtually no G 1 or G 2 phases this results in a reduction in cytoplasmic volume of each daughter cell with each cell division. See also Human oocyte to blastocyst
[110] Environment Effects on Embryo Development - Open Access Pub — Environment Effects on Embryo Development Embryo development is an incredibly complex, yet sensitive process that is greatly impacted by the environment. Numerous external factors, such as temperature, air quality, and light exposure, play an important role in the successful development of an embryo. Poor environmental conditions can lead to bad outcomes, including embryonic death
[111] Factors affecting the early embryonic environment — The early human embryo develops in a tightly controlled, relatively protected environment. During the first 8-12 weeks of human gestation, the delivery of maternal blood, and therefore the amount of oxygen to the developing embryo is limited and the embryo is supplied with essential nutrients in part via the decidual uterine glands, the placental trophoblast and the secondary yolk sac
[112] Environmental Alterations during Embryonic Development: Studying the ... — These changes in environmental conditions cause the embryo to optimise its future development program, resulting in a form of plasticity related to the concept of predictive adaptive responses in DOHaD . Moreover, studies in animal models have shown that the PC environment influences subsequent development programming in mammalians .
[113] Environmental Disruption of Normal Development - Developmental Biology ... — Most early embryonic and fetal demise is probably due to chromosomal abnormalities that interfere with normal developmental processes. Abnormalities caused by exogenous agents (certain chemicals or viruses, radiation, or hyperthermia) are called disruptions.
[133] What is embryology the study of? - California Learning Resource Network — Significance of Embryology. Embryology has significant implications for various fields, including: Reproductive Medicine: Understanding embryonic development is crucial for diagnosing and treating reproductive disorders, such as miscarriage, stillbirth, and birth defects.
[134] Why Is Embryology Important For Doctors — By integrating newer molecular medical embryology with the traditional approach to developmental of anatomy, embryology becomes an appropriate component of the standard medical curriculum. ... What Is The Clinical Significance Of Embryology? Embryology plays a crucial role in understanding human life and prenatal development, offering insights
[135] (PDF) Medical Embryology and its Importance in the 21st Century ... — The study of human embryology has theoretical (as a pre-clinical course during medical study), but also important clinical significance. Embryology is a fascinating field of science which can
[136] [PDF] Medical Embryology and its Importance in the 21st Century ... — A variety of aspects in which embryology could be presented as well as how it may be incorporated within the medical curriculum are outlined. Embryology is an essential tool in clinical practice especially for managing various medical disorders. As a course in medical schools, it is neither easy nor straightforward to understand and teach in the 21st century curriculum, as such, it is easy to
[143] Decoding the blueprints of embryo development with single-cell and ... — Single-cell and spatial omic technologies have recently emerged as formidable tools for deciphering the intricacies of cellular organization and the dynamics of gene expression throughout the course of tissue development , , , .In this review, we synthesize recent breakthroughs in embryonic development research utilizing these technologies, with a focus on key questions including
[144] Early human development and stem cell-based human embryo models — Recent advances have come from the establishment of stem cell lines representative of early human embryo lineages. 1, 2 Human pluripotent stem cells (PSCs) possess a high degree of cellular plasticity, which has enabled strategies to guide PSCs into multiple embryonic and extra-embryonic cell types. 3, 4, 5 Remarkable progress has been made in modeling the human and non-human primate embryo by
[145] Scientists program stem cells to mimic first days of embryonic development — Scientists at UC Santa Cruz were able to engineer cellular models of embryos without ever experimenting with any actual embryos, allowing them to mimic the first few days after two sexually reproductive cells meet. They use CRISPR-based engineering methods to prompt stem cells to organize into “programmable” embryo-like structures, also known as embryoids, which can be used to study the role of certain genes in early development. “These cells co-develop together, just like they would in an actual embryo, and establish that history of being neighbors,” Shariati said. The team found that 80% of the stem cells organize themselves into a structure that mimics the most basic form of an embryo after a few days, and most undergo gene activation that reflects the development process that occurs in living organisms.
[146] Deciphering the Mechanisms of Developmental Disorders (DMDD): a new ... — The 'Deciphering the Mechanisms of Developmental Disorders' (DMDD) programme has the ambitious goal of identifying all embryonic lethal knockout lines made in the UK over the next 5 years, and will use a combination of comprehensive imaging and transcriptomics to identify abnormalities in embryo structure and development.
[147] Artificial intelligence in human in vitro fertilization and embryology — Embryo evaluation and selection embody the aggregate manifestation of the entire in vitro fertilization (IVF) process. It aims to choose the "best" embryos from the larger cohort of fertilized oocytes, the majority of which will be determined to be not viable either as a result of abnormal development or due to chromosomal imbalances. Indeed, it is generally acknowledged that even after
[148] The Impact of Endometrioma on Embryo Quality in In Vitro Fertilization ... — It is already acknowledged that oocyte and embryo quality is vital to a successful outcome of in vitro fertilization (IVF). At present, a number of criteria for evaluating oocyte and embryo quality mainly based on morphological characteristics have been established to select high-quality oocytes and embryos for improving subsequent pregnancy
[153] The Future of IVF: The New Normal in Human Reproduction — Integration of microfluidics into the IVF laboratory may give rise to at least four foreseeable advantages: (1) precisely controlled fluidic gamete/embryo manipulations; (2) providing biomimetic environments for culture; (3) facilitating microscale genetic and molecular bioassays; and (4) enabling miniaturization and automation. Microfluidic in vitro insemination has been demonstrated , whereas conventional fertilization is suitable for the vast majority of IVF patients, microfluidic systems may further decrease the need for Intracytoplasmic Sperm Injection (ICSI). Noninvasive PGT, which utilizes cell-free DNA released into the spent embryo culture media, is likely to become the first omics technology used clinically in conjunction with a microfluidic system . IVF-on-a-chip: recent advances in microfluidics technology for in vitro fertilization. Integration of single oocyte trapping, in vitro fertilization and embryo culture in a microwell-structured microfluidic device.
[155] PDF — : Assisted Reproductive Technologies (ART) have revolutionized the treatment of infertility, offering hope to millions of couples worldwide. This comprehensive review examines the recent advancements in ART up to 2022, focusing on innovations in in vitro fertilization (IVF), preimplantation genetic testing (PGT), and emerging technologies. Through a systematic analysis of literature, this
[174] Stem Cell Therapies for Human Infertility: Advantages and Challenges — ADSCs are considered to be effective and important candidate cells for the treatment of male infertility as they contain pluripotent stem cells that can differentiate into any cell of the three germ layers. ... over 8 million babies have been born following IVF; however, the impact of ART on the health of both patients and their offspring
[176] The Future of IVF: The New Normal in Human Reproduction — Integration of microfluidics into the IVF laboratory may give rise to at least four foreseeable advantages: (1) precisely controlled fluidic gamete/embryo manipulations; (2) providing biomimetic environments for culture; (3) facilitating microscale genetic and molecular bioassays; and (4) enabling miniaturization and automation. Microfluidic in vitro insemination has been demonstrated , whereas conventional fertilization is suitable for the vast majority of IVF patients, microfluidic systems may further decrease the need for Intracytoplasmic Sperm Injection (ICSI). Noninvasive PGT, which utilizes cell-free DNA released into the spent embryo culture media, is likely to become the first omics technology used clinically in conjunction with a microfluidic system . IVF-on-a-chip: recent advances in microfluidics technology for in vitro fertilization. Integration of single oocyte trapping, in vitro fertilization and embryo culture in a microwell-structured microfluidic device.
[178] IVF Success Rates in 2025: Latest Advances, Costs, and Expert Insights — Recent data suggests a steady improvement in IVF success rates worldwide due to technological innovations and refined treatment protocols. Here's how success rates have changed: Global IVF success rates have risen by 5-10% since 2023. Increased use of AI-driven embryo selection has enhanced implantation chances. Time-lapse imaging has
[179] Synthetic Human Embryos: A Breakthrough or A Dilemma — What are the Issues Involved in the Development of Synthetic Human Embryos? Unclear Regulations: Synthetic human embryos may pose ethical challenges regarding their moral status, use, and regulation.
[181] Synthetic human embryos pose bioethical dilemmas - UCA News — Consequently, the potential utilization of synthetic embryos in human reproduction would undoubtedly provoke much more moral outrage and ethical controversy compared to its non-reproductive biomedical applications.
[182] Synthetic human embryo raises ethical issues - BBC — The synthetic embryos - only days or weeks old - could help researchers study the earliest stages of human development and explain pregnancy loss. The development of human synthetic embryos was announced at the annual meeting of the International Society for Stem Cell Research. But the principle is the synthetic embryos are made from a stem cell rather than a fusion of egg and sperm. Prof Briscoe said: "On the one hand, models of human embryos made of stem cells might offer an ethical and more readily available alternative to the use of IVF-derived [in-vitro fertilisation] human embryos. Researchers hope these synthetic embryos will further understanding of the earliest stages of human's lives. About the BBC
[184] AI Ethics In Reproductive Health - Restackio — In the context of reproductive health, ethical considerations in AI are paramount, given the sensitive nature of the data involved and the potential impact on individuals' lives. ... Engaging stakeholders, particularly those from underrepresented communities, is crucial in shaping ethical AI practices in reproductive health. This can be
[186] Artificial Intelligence in Human Reproduction - ScienceDirect — The use of artificial intelligence (AI) in human reproduction is a rapidly evolving field with both exciting possibilities and ethical considerations. This technology has the potential to improve success rates and reduce the emotional and financial burden of infertility. However, it also raises ethical and privacy concerns.
[188] Artificial Intelligence in Reproductive Medicine - An Ethical ... — Artificial intelligence is steadily being integrated into all areas of medicine. In reproductive medicine, artificial intelligence methods can be utilized to improve the selection and prediction of sperm cells, oocytes, and embryos and to generate better predictive models for in vitro fertilization. …
[189] Interpretable, not black-box, artificial intelligence should be used ... — Models for embryo selection run the risk of systematically selecting for these traits if they are perceived by the model to be correlated with implantation success. For example, if a patient prefers that sex be randomly selected, this model may run counter to those values. ... Evaluation of the Role of an Artificial Intelligence System (iDA) in
[190] Embryo Model Advances in Modern Biology - BiologyInsights — Discover how advanced embryo models are enhancing our understanding of early development, gene regulation, and tissue organization in modern biology. Studies in Nature Cell Biology have shown that fine-tuning these pathways can induce embryonic structure formation without fertilization, offering a controlled system for studying early development. A 2023 study in Science identified a subset of extraembryonic-like cells in synthetic embryos contributing to early patterning, suggesting these models can capture aspects of trophoblast and yolk sac development. Single-cell RNA sequencing (scRNA-seq) has shown that synthetic embryo models display transcriptional trajectories similar to natural embryos, with distinct gene expression waves marking developmental transitions. Despite their ability to replicate many features of early embryonic development, synthetic models differ from natural embryos in key aspects.
[192] Cells That Build Themselves Into an Embryo? Scientists ... - SciTechDaily — These lab-grown cell assemblies are not true embryos but closely mimic key aspects of early development, providing a powerful tool for studying genetic and environmental influences on embryonic formation. “We want to know how cells organize themselves into an embryo-like model, and what could go wrong when there are pathological conditions that prevent an animal from successfully developing.” This method had the advantage of allowing different cell types to “co-develop,” which more closely resembles the natural embryo formation than the chemical approaches other scientists have used to develop different cell types. The team found that 80% of the stem cells organize themselves into a structure that mimics the most basic form of an embryo after a few days, and most undergo gene activation that reflects the development process that occurs in living organisms.
[193] Current Status of Synthetic Mammalian Embryo Models - PMC — Research in this context has considerable implications for the advancement of regenerative medicine, as an understanding of these early developmental stages can inform strategies for tissue engineering and the treatment of developmental disorders. However, research on human embryos is fraught with ethical and regulatory challenges.
[194] Embryo Grading In IVF: What Does These Numbers Really Tell You? — Embryo grading offers a methodical assessment to help predict the success of embryo development. This evaluation focuses on several visual indicators that correlate with embryo health and developmental potential. A comprehensive assessment of factors ensures that the most viable embryos are chosen for transfer.
[196] IVF Embryo Grading and Success Rates, Explained by An Embryologist — An embryo transferred on the fifth day of development (as a blastocyst), is generally considered superior to a Day 3 embryo transfer due to higher pregnancy rates, better embryo selection, and a lower risk of multiple pregnancies, as the longer development time allows for a more thorough evaluation of the embryo's quality.
[197] Non-invasive assessment of embryo viability by metabolomic profiling of ... — for improved or new embryo viability assessment. Recently, a number of new, non-invasive embryo viability . tests have been introduced. These tests aim to measure specific molecules from the culture medium to determine what the embryo used or secreted (amino acids, proteins, specific molecules such as soluble human leukocyte antigen class G
[212] Ethics in embryo research: a position statement by the ASRM Ethics in ... — Ethics in embryo research: a position statement by the ASRM Ethics in Embryo Research Task Force and the ASRM Ethics Committee - ScienceDirect Search ScienceDirect Ethics in embryo research: a position statement by the ASRM Ethics in Embryo Research Task Force and the ASRM Ethics Committee Ethics in Embryo Research Task Force Research involving human embryos is ethically acceptable if it is likely to provide significant new knowledge that may benefit human health, well-being of the offspring, or reproduction. Previous article in issue Next article in issue Recommended articles ©2019 American Society for Reproductive Medicine, Published by Elsevier Inc. Recommended articles No articles found. Cookies are used by this site. For all open access content, the relevant licensing terms apply.
[213] An ethical framework for human embryology with embryo models — Embryo models provide a new way to study development, yet their use has raised several questions. In this Perspective, the authors argue that answering those questions requires both a refined legal definition of an embryo and a decision about "tipping points" after which embryo models might be considered embryos.
[214] Ethics in embryo research: a position statement by the ASRM Ethics in ... — Ethics in embryo research: a position statement by the ASRM Ethics in Embryo Research Task Force and the ASRM Ethics Committee - PubMed Ethics in Embryo Research Task Force 1 ; Ethics Committee of the American Society for Reproductive Medicine. Electronic address: asrm@asrm.org 1 ; Ethics Committee of the American Society for Reproductive Medicine Ethics in Embryo Research Task Force et al. Ethics in Embryo Research Task Force 1 ; Ethics Committee of the American Society for Reproductive Medicine. Electronic address: asrm@asrm.org 1 ; Ethics Committee of the American Society for Reproductive Medicine Research involving human embryos is ethically acceptable if it is likely to provide significant new knowledge that may benefit human health, well-being of the offspring, or reproduction. Electronic address: ASRM@asrm.org; Ethics Committee of the American Society for Reproductive Medicine.
[224] The ethics of human-embryoids model: a call for consistency — In this article, we discuss the ethics of human embryoids, i.e., embryo-like structures made from pluripotent stem cells for modeling natural embryos. We argue here that it is time to reconsider the full ban on embryo research (human embryos and embryoids) beyond the 14-day rule and that research on those entities should obey a sliding scale combining the completeness of the model (e.g., complete vs. The 2016 guideline of the International Society for Stem Cell Research (ISSCR; Box 1) suggests that research involving embryoids that might manifest “human organismal potential” be reviewed by a proposed human Embryo Research Oversight (EMRO) process and prohibited if they violate the 14-day rule” . Toward guidelines for research on human embryo models formed from stem cells.
[225] The Moral Status of the Embryo - The Human Journey — The lowered status of the human embryo was given statutory force in the 1990 Human Fertilisation and Embryology Act, (13) which allows embryo freezing, experimentation and disposal up until 14 days after fertilisation. A philosophical defence . Biologically the human embryo is undoubtedly human; it has human chromosomes derived from human gametes.
[227] The moral status of the embryo - archive.cmf.org.uk — The moral status of the human embryo is central to contemporary debates on the ethics of cloning, embryo research, stem cell research, genetic engineering, assisted reproduction, preimplantation diagnosis, genetic screening, post-coital contraception and the production of chimaeras and 'non-organismal entities'.
[228] The moral status of the embryo: the human embryo in the UK Human ... — The ethical, moral and legal status of the human embryo has attracted much interest while provoking passionate debate on both sides. Lockwood defines the moral status of the embryo by delineating the concept of personhood, that it is the cluster of capacities which distinguish us from non-human animals,
[253] How will our understanding of human development evolve over the next 10 ... — In the next 10 years, the continued exploration of human embryology holds promise to revolutionize regenerative and reproductive medicine with important societal consequences. In this Comment we speculate on the evolution of recent advances made and
[256] Embryo Model Advances in Modern Biology - BiologyInsights — Discover how advanced embryo models are enhancing our understanding of early development, gene regulation, and tissue organization in modern biology. Studies in Nature Cell Biology have shown that fine-tuning these pathways can induce embryonic structure formation without fertilization, offering a controlled system for studying early development. A 2023 study in Science identified a subset of extraembryonic-like cells in synthetic embryos contributing to early patterning, suggesting these models can capture aspects of trophoblast and yolk sac development. Single-cell RNA sequencing (scRNA-seq) has shown that synthetic embryo models display transcriptional trajectories similar to natural embryos, with distinct gene expression waves marking developmental transitions. Despite their ability to replicate many features of early embryonic development, synthetic models differ from natural embryos in key aspects.
[262] How can we regulate embryo model research without stifling it? — The UK is a world leader in the regulation of fertility treatment and research involving human embryos, but advances in our ability to create and culture human stem cell-based embryo models is pushing us into an ethical grey area. Guidance is needed if we are to navigate this successfully - making the most of its potential while maintaining public trust and adhering to our values.
[264] Synthetic human embryo raises ethical issues - BBC — The synthetic embryos - only days or weeks old - could help researchers study the earliest stages of human development and explain pregnancy loss. The development of human synthetic embryos was announced at the annual meeting of the International Society for Stem Cell Research. But the principle is the synthetic embryos are made from a stem cell rather than a fusion of egg and sperm. Prof Briscoe said: "On the one hand, models of human embryos made of stem cells might offer an ethical and more readily available alternative to the use of IVF-derived [in-vitro fertilisation] human embryos. Researchers hope these synthetic embryos will further understanding of the earliest stages of human's lives. About the BBC
[266] Artificial intelligence in the in vitro fertilization laboratory: a ... — The integration of artificial intelligence (AI) and deep learning algorithms into medical care has been the focus of development over the last decade, particularly in the field of assisted reproductive technologies and in vitro fertilization (IVF). With embryo morphology the cornerstone of clinical decision making for IVF, the field of IVF is highly reliant on visual assessments that can be
[273] (PDF) CRISPR and Regenerative Medicine: Unlocking ... - ResearchGate — Advances in CRISPR-driven stem cell engineering, AI-enhanced gene targeting, and 3D bioprinting are paving the way for personalized regenerative therapies, offering hope for patients with
[274] How 3D Bioprinting is Shaping the Future of Regenerative Medicine — The landscape of 3D bioprinting is evolving at an unprecedented pace, pushing the boundaries of what's possible in regenerative medicine, tissue engineering, and biomedical research. Innovations in bioprinting technology are enabling researchers and clinicians to fabricate complex biological structures with unmatched accuracy and
[275] 3D Printing in Regenerative Medicine: Technologies and Resources ... — Three-dimensional bioprinting is vital in tissue engineering, which aims to create functional tissues for use in regenerative medicine and drug testing. Bioprinting can provide patient-specific spatial geometry, controlled microstructures, and the positioning of diverse cell types for the fabrication of tissue engineering scaffolds.
[286] Recognizing the ethical implications of stem cell research: A call for ... — The ethical implications of stem cell research are often described in terms of risks, side effects, safety, and therapeutic value, which are examples of so-called hard impacts. Hard impacts are typically measurable and quantifiable. To understand the broader spectrum of ethical implications of stem cell research on science and society, it is
[289] Ethical and Safety Issues of Stem Cell-Based Therapy - PMC — The creation and clinical use of hESCs have long been the unique focus of stem cell ethics. Current ethical controversies regarding stem cell-based therapy are focused on the unlimited differentiation potential of iPSCs which can be used in human cloning, as a risk for generation of human embryos and human-animal chimeras.
[290] Ethical issues in stem cell research and therapy - PMC — In this review of selected major ethical issues in stem cell research and therapy, we briefly describe and discuss the most significant ethical implications of this wide-ranging and fast-moving field. ... for researchers to keep in mind the population-level applications of stem cell research as well as the effects of stem cell therapy on
[291] Stem cell therapies in age-related neurodegenerative diseases and ... — Although much research remains to be completed to ensure safety, tolerability, and efficacy of stem cell delivery in aged populations and to further optimize the delivery protocols, stem cell therapy is a promising approach for the future treatment for age-related neurodegenerative diseases and stroke.