Transforming growth factor-α, epidermal growth factor, and epidermal growth factor receptor in human testis obtained from biopsy and castration: Immunohistochemical study

We analyzed expression of transforming growth factor (TGF)-α, epidermal growth factor (EGF) and their receptor, EGF receptor (EGFR), by immunohistochemistry in the human testis to determine the possible roles of these growth factors in human testicular function. Specimens were obtained from 17 patients including 9 patients with infertility, 4 patients with prostatic carcinoma and 4 patients with contralateral testicular tumor. EGF immunoreactivity was positive in the hyperplasic Leydig cells of one patient but negative in the other cases. On the other hand, strong TGF-α immunoreactivity was observed in Leydig cells, with weak staining in Sertoli cells and germ cells in cases with normal spermatogenesis. EGFR immunoreactivity was observed in the Leydig and peritubular cells, appearing as membrane staining. Marked immunoreactivity for TGF-α was observed in the Sertoli cells in testes with decreased spermatogenesis, especially in the Sertoli-cell-only syndrome. This finding may indicate a compensatory increase of TGF-α expression in the Sertoli cells accompanying a decrease in spermatogenesis. No significant correlation was found between the degrees of spermatogenesis and immunolocalization of the EGF receptor. These findings suggestthat TGF-α is a locally produced growth factor that is involved in spermatogenesis in the human testis via an autocrine and/or paracrine mechanism.