Effect of vitamin A deprivation on the mitogenic factor activity in the rat testes

The seminiferous tubules of rat testes contain a protease and heat sensitive factor capable of stimulating (3H)-thymidine incorporation into quiescent cultures of NIH 3T3 mouse fibroblast cells. This mitogenic factor activity was only 4% in the testes of vitamin A deficient-retinoic acid maintained rats as compared to that of normal rats. Supplementation of retinyl acetate to these vitamin A deficient rats for 4 days resulted in a 56% recovery in the mitogenic factor activity while by day 16, the recovery was 80 percent. Incorporation of (3H)-thymidine into DNA of the seminiferous tubules of vitamin A deficient rats was only 46% of that of normal rats which was restored to normal levels by retinyl acetate supplementation for 24 days.