Assessment of the role of Leydig cell products other than testosterone in spermatogenesis and fertility in adult rats

Adult male rats were treated with ethane dimethanesulphonate (EDS) to destroy the Leydig cells and were then supplemented for 3-10 weeks with testosterone esters (TE) by injection every 3 days. The latter treatment prevented Leydig cell regeneration but maintained quantitatively the androgen-dependent aspects of spermatogenesis, as judged by germ cell counts at stage VII of the spermatogenic cycle. Other than the absence of Leydig cells, the testes of EDS-treated, TE-supplemented rats showed only two morphological changes, (1) the appearance of mast cells throughout the interstitium, and (2) a 3- to 4-fold increase in the number of degenerating germ cells (secondary spermatocytes) at stages XIV-I; this was reflected in a significant decrease in the ratio of spermatids to pachytene spermatocytes at stage VII. These changes were not observed in either oil-treated or TE-treated control rats although similar, but less marked, changes in cell degeneration at stages XIV-I were observed in rats actively immunized against oxytocin. Epididymal sperm number was reduced marginally (approximately 15%) in EDS-treated, TE-supplemented rats while sperm motility was affected even less. In a serial mating trial, some of these treated rats showed evidence of subfertility/infertility, but this was mostly transient and may have been the result of epididymal effects of EDS. These results suggest that Leydig cell products other than testosterone are not essential for maintenance of spermatogenesis and fertility in rats, although because of increased germ cell degeneration during the final stages of meiosis (perhaps as the result of oxytocin withdrawal), a small reduction in sperm count may occur.