Distribution of basic fibroblast growth factor in the 18-day rat fetus: localization in the basement membranes of diverse tissues.

TLDR

The study discusses how basic FGF’s distribution informs its role in regulating cell proliferation and differentiation. Immunohistochemical staining was performed on 18‑day rat fetal tissues to map basic FGF localization. Immunostaining revealed that basic FGF is broadly distributed in mesenchymal structures, mesoderm‑ and neuroectoderm‑derived cells, and their extracellular matrices, with strong signals in skeletal and smooth muscle cells, basement membranes of epithelia, and endocrine cells of adrenal cortex, testis, and ovary, and its intensity varies with differentiation stage, supporting its role in mediating mesenchyme‑driven growth and differentiation.

Abstract

Immunohistochemical methods were used to study the distribution of basic FGF in the 18-d rat fetus. The results reveal a pattern of widespread yet specific staining that is consistent with the wide distribution of basic FGF. Immunoreactive basic FGF is associated with mesenchymal structures, mesoderm- and neuroectoderm-derived cells, and their extracellular matrices. As an example, skeletal and smooth muscle cells are strongly positive. The basement membrane underlying the epithelia always contain basic FGF. In some tissues (i.e., cartilage and bone) the intensity of immunostaining is dependent on the stage of cell differentiation. Although the staining of tissues is primarily associated with the extracellular matrix, there is significant intracellular staining in various cell types. This is particularly evident in the endocrine cells of the adrenal cortex, testis, and ovary. The histochemical findings reported here support the notion that basic FGF has the characteristics required to mediate many of the effects of the mesenchyme on cell growth and differentiation. The significance of these findings in understanding the role of basic FGF in regulating cell proliferation and differentiation is discussed.