Expression of TGFbeta3 RNA during chick embryogenesis: a possible important role in cardiovascular development.

We examined the temporal and spatial expression pattern of transforming growth factor (TGF)-beta3 RNA during chick embryogenesis from stage 6 to stage 33 (Hamburger and Hamilton scale) by using in situ hybridization. During cardiogenesis, TGFbeta3 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 TGFbeta3 was found in smooth muscle progenitor cells, but not in endothelium. In addition, TGFbeta3 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 TGFbeta3 plays an important role in the development of the cardiovascular system and of other mesodermal derivatives during chicken embryogenesis.