Penetration of exogenous testosterone, pregnenolone, progesterone and cholesterol into the seminiferous tubules of the rat.

Abstract

Tritiated cholesterol, pregnenolone, progesterone and testosterone were injected intravenously into adult male rats. They were killed from 30 min to 10 days after the injection of cholesterol, and from 2 to 30 min after the other steroids. The interstitial tissue of the testis was separated by free hand dissection from the seminiferous tubules. The tissue samples were dried, weighed, combusted in closed glass ampules and the tritium gas was subsequently counted in a metal cathode internal gas counter. Pregnenolone, progesterone and testosterone behaved equally, producing maximal radioactivity in both tissue compartments between 2 and 5 min after the injection, but the maximal radioactivity appeared at 24 hr after the cholesterol injection. The radioactivity in the seminiferous tubules was always significantly lower than in the interstitial tissue, the difference being most marked in the case of cholesterol. Very low or negligible counts were obtained in the seminiferous tubules throughout the cholesterol ...