Addition of androgens to cultured hamster epididymis increases zona recognition by immature spermatozoa

The ability of spermatozoa recovered from the successive segments of the hamster epididymis to bind to the zona pellucida was studied and a major increase was found as spermatozoa passed from the proximal to the distal portion of the corpus epididymidis (1.95 compared with 20 spermatozoa bound/egg). Tubules from the proximal epididymis were cultured in conditions which preserved the motility of the contained spermatozoa for 48-72 h. Addition of 2 microM-5 alpha-DHT to the culture medium for 17 h stimulated the incorporation of 3H-labelled amino acids into several protein bands whose mobility in polyacrylamide gel electrophoresis was coincident with those of glycoproteins EP1-EP6, previously identified as androgen-dependent in the hamster epididymis in vivo. Examination of the material extracted from washed spermatozoa with 0.5 M-NaCl revealed the presence of radioactive proteins on spermatozoa. The zona-binding ability of spermatozoa from androgen-treated cultured proximal corpus tubules was significantly increased (P less than 0.001) as was the no. of spermatozoa/egg (5.51) compared with the value for control cultures (0.87 spermatozoa/egg). We suggest that androgen-dependent epididymal secretory proteins that associate with spermatozoa might participate in the formation or activation of a site for zona pellucida recognition in the sperm surface.