Local Stimulatory Effect of Vitamin A on Spermatogenesis in the Rat

Abstract

The objectives of this study were: (1) to see if a localized effect of retinol could be demonstrated on the germinal epithelium of rat testes and (2) to determine if retinoic acid administered directly into the testis would support spermatogenesis. When 10 µg of retinol in oil was injected intratesticularly into vitamin A-deficient rats, marked stimulation of the germinal epithelium around the injection site occurred in 14 days. A larger amount of retinol, 400 µg, injected under the testicular capsule or the implantation of a 3 mg pellet restored spermatogenesis throughout the testis, and also in the corresponding untreated testis, in 50 days. Substitution of retinoic acid or its methyl ester in the above procedures was completely ineffective. Retinoic acid when combined with retinol in an implanted pellet did not interfere with the stimulatory activity of the retinol. It is concluded that retinol has a local direct biochemical action on the germinal epithelium and that retinoic acid is totally inactive.