Maturation of spermatozoa in the rabbit epididymis: Effect of castration and testosterone replacement

Rabbit epididymal spermatozoa gain their fertilizing ability upon reaching the distal corpus epididymidis. When prevented by ligatures from reaching this region, they become fertile in the proximal corpus after 24 hours in the intact male but not in the three‐day castrated male. Unilateral castration has no such effect. Testosterone propionate (2 mg/kg/day) prevents this effect of castration. Abnormalities in ova fertilized by spermatozoa from castrated males and castrated males receiving testosterone suggest that an adequate level of androgen is necessary not only for the spermatozoa to become fertile but, also, for support of the normal development of the ova.