RELATIONSHIP BETWEEN SUBMANDIBULAR-GLAND EPIDERMAL GROWTH-FACTOR AND SPERMATOGENESIS IN C3H MICE

Epidermal growth factor (EGF), a potent mitogen produced primarily in the submandibular gland of adult male mice, has been implicated in mod ulating processes known to be of vital importance in the regulation of spermatogenesis. In the present investigation we demonstrate that sub mandibular gland EGF from adult male mice is indeed capable of displac ing radiolabeled EGF from testicular membranes. Scatchard analysis of this binding site reveals that it is of high affinity (K-d = 0.7 nM) a nd low capacity (B-max = 8.15 fmol/mg protein). Cross-linking of I-125 -EGF to the identical membrane preparation resulted in the SDS-PAGE/au toradiography identification of a single band at approximately 170 kDa . Next, we examined the cellular distribution of the EGF receptor in t he testis using biotin-streptavidin immunoperoxidase and employing dif ferent antisera probes generated to a conserved sequence of the EGF re ceptor. The Scatchard and cross-linking data described above, along wi th the immunocytochemistry results, suggest strongly that there is onl y one functional binding site for EGF in the adult testis and that thi s receptor is present in Sertoli and Leydig cells.