Sertoli cells and development of seminiferous epithelium

Abstract

Sertoli cells partially control development of the seminiferous epithelium and spermatogenetic processes in mammals. Hypophysectomy of impuberal lambs results in a decrease in the total number of Sertoli cells/testis while that of stem cells/testis is maintained. Type Ao spermatogonia divide but few type Al spermatogonia are observed. There is no development of seminiferous epithelium. LH only, or FSH + LH supplementation respectively maintains or stimulates mitotic activity of Sertoli cells. FSH or LH acts on the differentiation of spermatogonia. Hemicastration of the impuberal rat and calf results in an increase in Sertoli cell and stem cell numbers in the remaining testis. Sertoli cell stocks are depressed after posthemicastration treatment with either testosterone or testis protein extract. Stem cell stocks are only affected by treatment with testis protein extract. Rat testicular compensatory hypertrophy is also inhibited by rete testis fluid. In the prepubertal rat or lamb where mitotic acitivity of supporting cells has almost stopped, hypophysectomy results in a decrease in Sertoli cell number/testis. Stem spermatogonia number/testis and the efficiency of spermatogenesis are largely decreased. FSH supplementation maintains these parameters in the rat. In the remaining testis of the prepubertal hemicastrated rat or calf Sertoli cell stocks are not modified while stem cell stocks are increased. Positive correlations between the total numbers of Sertoli cells, the total length of seminiferous tubules/testis and the total area of seminiferous epithelium have been observed in adult males of different species (rat, ram, bull). The total number of Sertoli cells/testis and stem cell stocks/testis were also correlated. After hypophysectomy of adult animals (rat or ram) Sertoli cell stocks/testis do not vary while spermatogonia stock and the efficiency of the spermatogenetic process are greatly affected. In the adult rat, stem spermatogonia and yield of spermatogonial divisions are maintained by FSH treatment while meiosis and spermiogenesis are supported by LH supplementation. In the hypophysectomized ram, testosterone treatment does not support normal spermatogenesis.