Hormonal requirements of the different cycles of the seminiferous epithelium during reinitiation of spermatogenesis in long-term hypophysectomized rats.

Restoration of testicular function in long-term hypo-physectomized rats given different hormonal treatments during the various cycles of the seminiferous epithelium was evaluated on the basis of the weights of testes, epididymides, and other accessory sexual glands, histological examination of testes, and determination of the numbers of spermatozoa/epididymis. The staput fractionation technique for the separation of classes of germinal cells was employed to provide a measure of the advancing front of pulse-labelled cells following the intratesticular administration of (3-H)thymidinemthe results suggested that during the first two cycles, in which spermatogonia develop into pachytene spermatocytes, either LH or testosterone alone was sufficient for partial restoration. During the third cycle of the seminiferous epithelium, LH and FSH were required to allow previously labelled pachytene spermatocytes to progress efficiently to stage 7 spermatids. Administration of LH alone during the final cycle was sufficient to permit stage 7 spermatids to develop into spermatozoa, provided LH plus H had been given during the previous three cycles. Injection of LH during the entire period and of FSH during the third cycle of the seminiferous epithelium was required to achieve Staput profiles characteristic of a normal advancing front of pulse-labelled cells, and to allow partial restoration of spermatogenesis. More complete restoration was obtained in rats given FSH and LH during the first three cycles but, with the doses employed, the number of spermatoza/testis remained subnormal. Efficient completion of each cycle of the seminiferous epithelium appeared to be hormone-dependent. The data are discussed in relation to the possibility that hormones may affect the general development of germinal cells in an indirect manner by their influence on Sertoli cell function.