INFLUENCE OF PROLACTIN AND PITUITARY ISOGRAFTS ON SPERMATOGENESIS IN DWARF MICE AND HYPOPHYSECTOMIZED RATS

Abstract

SUMMARY: This work was undertaken to study the influence of purified prolactin on spermatogenesis in hypophysectomized rats with or without testosterone propionate maintenance therapy and in prolactin-deficient hereditary dwarf mice. In addition some dwarf mice were given heterotopic isografts of non-dwarf mice pituitaries. In rats, 25 i.u. ovine prolactin given daily for 33 days had no effect on the maintenance of spermatogenesis. In untreated dwarf mice spermatogenesis progressed to completion but had a low yield due to cell loss, especially during premeiotic divisions. Both 10 i.u. prolactin daily for 28 days and pituitary grafts resulted in marked stimulation of spermatogenesis. The number of preleptotene and pachytene spermatocytes and step 7 spermatids was significantly increased in both inbred and F₁ dwarf mice regardless of age. Since seminal vesicles were also considerably heavier in treated dwarfs, it was concluded that the observed stimulation of spermatogenesis was most likely due to elevated testicular androgen production indicating that, in the male mouse, prolactin may be involved in pituitary regulation of Leydig cell function.