No abstract

No abstract

No abstract

No abstract

The effects of sheep interstitial cell-stimulating hormone (ICSH) and follicle-stimulating hormone (FSH) on spermatogenesis were studied in rats of the Long-Evans strain six months after removal of the pituitary gland. The results confirm the contention that sheep ICSH alone is not an effective agent for stimulating repair of the epithelium of the seminiferous tubules of the rat, and that preparations of sheep FSH contain a principle which, in the presence of less than 1 \g=m\g of ICSH per day, can stimulate substantial repair. All the effects obtained with gonadotrophin preparations can be accomodated if one assumes that FSH is specifically concerned with some critical step in the evolution of the primary spermatocyte and that androgen is responsible for maintaining a favorable intratubular environment in which the germ cells can develop. A complication encountered in this study was an unexpected variation in the germ cell population of rats that had been hypophysectomized for a period of 6 months; the possibility that residual gonadotrophin may account for this observation is discussed.The status of our knowledge of the relationship of the gonadotrophins to spermatogenesis has recently been assessed (Woods 8c Simpson 1961;Lostroh 1962). Experiments in hypophysectomized animals injected with the gonado¬ trophins shortly after the operation have established that interstitial cell-*