Viability and differentiation of human trophoblast in organ culture

Abstract

Abstract Organ culture of 15 immature human placentas — obtained at therapeutic abortion of 5–22 week gestations — was carried out in a medium consisting of: horse serum, 20%; NCTC 109, 15%; and balanced salt solution, 65% to which was added 100 I.U. of penicillin per ml of culture medium. Minced placental fragments were placed on filter paper laid across glass beads within a Petri dish; the medium barely covering the beads. Moist incubation was carried out at 35–36°C in a mixture of 5% CO 2 and 95% O 2 for 4–6 weeks; the medium being changed every 2–3 days. Radioautographic techniques using 1–2 μc of methyl H 3 ‐thymidine per ml of medium as well as routine histological techniques were employed. These showed that Langhans epithelium or cell masses — cytotrophoblast — differentiated or metamorphosed into a “new” syncytiotrophoblast. Only cytotrophoblastic nuclei took up the radioactive thymidine which appeared later in the new syncytiotrophoblast. Ordinary histologic preparations showed that the “new” syncytiotrophoblast resembled the original syncytiotrophoblast by virtue of its position (between original cyto‐ and syncytiotrophoblast) together with its loss of cell boundaries and its acquisition of intracellular vacuoles and cytoplasmic chromophilia. The cytotrophoblast remained viable for three weeks and then gradually decreased in amount with a corresponding increase in the amount of “new” syncytiotrophoblast. The latter was the predominant though necrotic tissue seen at six weeks. These techniques are tools for investigating the many aspects of growth, differentiation and endocrine function of human trophoblast.