THE EXPRESSION OF TRANSFORMING GROWTH-FACTOR-BETA GENES IN DEVELOPING CHICK WINGBUD

In the developing chick embryos, several kinds of growth factors are known to play some major roles in the process of pattern formation and tissue differentiation. The present study was performed to examine the expression profile of transforming growth factor beta's (TGF-B) in the early phase of chick wing development. The level of TGF-beta 1 and TGF-beta 2 gene expression increased with the advancing stages of chick wing development even though the amount of increase was not profound. In the case of TGF-beta 3, the level of gene expression at 5 days post-incubation was somewhat lower than that at 4 days post-incubation while the level increased again at 6 days post-incubation. Among the three TGF-beta's, the level of TGF-beta 2 expression was most strong while the level of TGF-beta 1 expression was most weak. Examination of spatial expression pattern of TGF-beta 2 in the developing wingbud revealed that the expression was high at the region of apical ectodermal ridge at 4-5 days post-incubation, and, in the anterior and posterior necrotic zones, the signal intensity became strong with advancing developmental stages. The results obtained in the present study suggest that TGF-beta's play some role(s) in the wing pattern formation, especially during early phase of chick wing development.