Expression of TGFβ3 RNA during chick embryogenesis:: a possible important role in cardiovascular development

We examined the temporal and spatial expression pattern of transforming growth factor (TGF)-beta 3 RNA during chick embryogenesis from stage 6 to stage 33 (Hamburger and Hamilton scale) by using in situ hybridization. During cardiogenesis, TGF beta 3 mRNA was first expressed in the premyocardium at stage 8 and thereafter it was localized in endocardial cushion tissue and the ventricular myocardium until the end of embryogenesis. During the formation of the major arteries, mRNA for TGF beta 3 was found in smooth muscle progenitor cells, but not in endothelium. In addition, TGF beta 3 mRNA was detectable in various mesoderm-derived tissues, such as the notochord, myotome, pleura, peritoneum, mesenchymal cells in the limb, and developing bone. These results suggest that TGF beta 3 plays an important role in the development of the cardiovascular system and of other mesodermal derivatives during chicken embryogenesis.