Inhibition of FSH affects spermatogenesis in the mature ram

We examined the effect of immunosuppression of follicle stimulating hormone (FSH) on spermatogenesis in adult rams in the breeding season. Rams were immunised for 20 days with one of two anti-FSH antisera, AS1 ( n=5) or AS2 ( n=5) and spermatogenesis compared with that of control rams ( n=4) treated with equine γ-globulins. Treatment with either AS1 or AS2 had no effect on the number of Sertoli cells or A 0 spermatogonia per testis nor on the daily production of A 1 spermatogonia or of spermatids. However, treatment with either AS1 or AS2 significantly decreased the nuclear size of the Sertoli cells, the daily production of B 2 spermatogonia and of leptotene spermatocytes. Treatment with AS1 also decreased the daily production of pachytene spermatocytes. Neither anti-serum affected the secretion of testosterone or luteinising hormone (LH). This experiment has shown that FSH is necessary for normal spermatogenesis in the adult ram because, between the development from A 1 to B 2 spermatogonia, there exists a step which is sensitive to FSH deprivation. This effect is probably mediated through an impairment of Sertoli cell function.