THE EFFECTS OF PROLACTIN ADMINISTRATION ON THE INTERNAL RHYTHM OF REPRODUCTION IN MALE BIRDS

Abstract

SUMMARY: A single intramuscular injection of 1 mg (20–25 i.u.) prolactin leads to a metamorphosis of the seminiferous tubules of the avian testis involving inhibition of spermatogenesis, massive steatogenesis in the region occupied by the germinal elements and appearance of profuse cholesterol in the newly formed lipid material. These events appear to be identical with the postnuptial testis metamorphosis that occurs in all birds so far studied, as well as with the condition observed after hypophysectomy. The possible significance of prolactin in the avian sexual cycle (apart from crop-gland development in Columbiformes) is discussed.