ABSTRACT
The roles of TGF-beta1, beta2 and beta3 according to gestational ages and histodifferentiation were studied using immunohistochemistry with rat fetuses. 1. From day 14 to 21 of fetal rat, all the TGF-beta1, beta2 and beta3 were expressed in endocardium, myocardium, bronchiole, tunica intima of blood vessles, mucosa and serosa of intestine, striated muscle, hepatic capsule, hepatic hemopoietic cells, meninges, epidermis and dermis. 2. From day 14 to 21 of fetal rat, TGF-beta1 was not expressed in the smooth muscle of blood vessel and intestinal tract, alveolar cell and renal tubular cell. TGF-beta2 was not expressed in the smooth muscle of blood vessel and intestinal tract and alveolar cell. TGF-beta3 was not expressed in osteocyte, alveolar cell, and basement membrane of renal cuboidal epithelial cell. And TGF-betas expressed especially in early or late gestational age and the degree of expression increased or decreased with gestational age. 3. The TGF-beta1, beta2 and beta3 were expressed in tissues originated from 3 germ layers except several tissues, and those originated from mesoderm exhibited strong expression. The TGF-beta1 was expressed more widely than TGF-beta2 and beta3 during gestation. In summary, TGF-beta1, beta2 and beta3 were considered as important control factors of cell to cell interaction in the morphogenesis of tissues during fetal development.