[The mechanism of the thymolytic action of anabolic steroids].

The administration of testosterone and metandrostenolone to male rats in doses of 10 and 20 mg/kg for 10 days produced a decrease of the thymus mass and a reduction of the thymic serum factor content. A phytoecdisteroid ecdisterone not possessing the androgenic activity fails to influence the thymus mass and the content of the thymic serum factor.