Expression of the Tgfß2 Gene During Chick Embryogenesis

We performed a comprehensive analysis of the expression of transforming growth factor (TGF) beta 2 during chick embryogenesis from stage 6 to 30 (Hamburger and Hamilton, J Morphol 1951;88:4992) using in situ hybridization. During cardiogenesis, Tgf beta 2 was expressed in the endothelial/mesenchymal cells of the valvulo-septal endocardial cushion tissue and in the epicardium until the end of embryogenesis. During the formation of major arteries, Tgf beta 2 was localized in smooth muscle progenitors but not in the vascular endothelium. During limb development, Tgf beta 2 was expressed in the mesenchymal cells in the presumptive limb regions at stage 16, and thereafter it was localized in the skeletal muscle progenitors. In addition, strong Tgf beta 2 expression was seen in the mesenchymal cells in the pharyngeal arches. Tgf beta 2 mRNA was also detected in other mesoderm-derived tissues, such as the developing bone and pleura. During ectoderm development, Tgf beta 2 was expressed in the floor plate of the neural tube, lens, optic nerve, and otic vesicle. In addition, Tgf beta 2 was expressed in the developing gut epithelium. Our results suggest that TGF beta 2 plays an important role not only in epithelial-mesenchymal interactions but also in cell differentiation and migration and cell death during chick embryogenesis. We also found that chick and mouse Tgf beta 2 RNA show very similar patterns of expression during embryogenesis. Chick embryos can serve as a useful model to increase our understanding in the roles of TGF beta 2 in cellcell interactions, cell differentiation, and proliferation during organogenesis. Anat Rec, 2012. (C) 2011 Wiley Periodicals, Inc.