Immunohistochemical localization of transforming growth factor-alpha and epidermal growth factor-receptor in the mesonephros and metanephros of the chicken.

Transforming growth factor-alpha (TGF-alpha) is a polypeptide related to epidermal growth factor (EGF). Both bind to EGF-receptor (EGF-R) to carry out their function in a variety of tissues and cell lines. Several studies have shown their presence in mammalian kidney, however, nothing has to date been stated concerning their existence in avian kidney. Expression of TGF-alpha and EGF-R is reported here for the first time during the development of the chicken kidney. Using immunohistochemical techniques, we identified a TGF-alpha (but not EGF) in mesonephric distal tubule cells from day 8 to day 20 of embryonic development and in metanephric distal tubule cells from day 14 of embryonic development to the adult. The histochemical characteristics of these cells and their histological localization suggest that they may be the "principal cells" of the distal tubules. Similarly, EGF-R was found in mesonephric proximal tubule cells from day 7 to day 18 of embryonic development and in metanephric proximal tubule cells from day 13 of embryonic development up to adult stages. The coexistence of both TGF-alpha and EGF-R from the onset of development of mesonephros and metanephros supports their possible role in mechanisms of proliferation and differentiation of the cells of these organs.