Regulation by FSH and ICSH(LH) of Reproductive Function in the Immature Male Rat

Requirements for FSH and ICSH (LH) in male reproduction have been evaluated in immature rats of the Sprague-Dawley strain; animals were hypophysectomized at 28 days of age and hormone injections initiated 2 months later. Combinations of extensively purified ovine FSH and ICSH of high specific activity established spermatogenesis in the seminiferous tubules of the retrogressed testis, and promoted copious androgen secretion as evidenced by growth of the sex accessory organs. FSH, given together with ICSH, markedly enhanced androgen production. Alone, individual hormones effected only limited development of the seminiferous tubules in these immature animals. FSH stimulated Sertoli cell development but no advance in germ cell maturation. Testosterone stimulated primary spermatocytes to complete meiosis, as did ICSH; with neither hormone did spermiogenesis proceed beyond the early spermatid stage. In individual rats, production of spermatozoa was correlated with high androgen secretion. However, exogenous androgen, unlike its action in the hypophysectomized mature rat, failed to instate sperm production in these immature animals; FSH plus testosterone was no more effective than testosterone alone. Limited success was realized in establishing full reproductive function when both ovine gonadotropins were injected over a period of 75 days; failure of 50 % of treated males to impregnate females was correlated with a limited capacity to produce androgen and with the presence of large numbers of desquamated germ cells in the epididymis. (Endocrinology85: 438,1969)