Reinitiation and Restoration of Spermatogenesis with Testosterone Propionate and Other Hormones After a Long-Term Post-hypophysectomy Regression Period

Abstract

The ability of testosterone propionate (TP) to restore spermatogenesis was investigated in 67- to 70-day hypophysectomized rats administered TP either separately or in combination with somatotrophin (STH) and/or thyroxine (T4). Following TP treatment for 35 days, the testicular weights had increased to twice those of the hypophysectomized controls, and a few of the seminiferous tubules contained germinal cells as mature as acrosome phase spermatids. With more prolonged therapy (90–110 days), spermatogenesis was restored qualitatively but not quantitatively in 33% of the animals, while the remainder of the animals showed varying degrees of response. The testes of animals given TP+STH or TP+STH+T4 for 35 days were heavier than those of animals receiving TP alone, and a few of the seminiferous tubules contained maturation phase spermatids. Treatment for 90–110 days completely restored spermatogenesis in ½ of these animals. Consequently, although testosterone alone can restore spermatogenesis to a limited extent, the addition of STH appears to augment this effect significantly. Following total post-hypophysectomy regression of the testes, some seminiferous tubules apparently lose the ability to respond to hormonal stimulation. In contrast, complete morphologic and functional restoration of the male reproductive system is possible in some animals if therapy is continued for sufficient periods of time.