The Endocrinology of Spermatogenesis in Birds

THE role of the thyroid hormone, thyroxine, in reproduction in mammals has received considerable study especially in the female. In poultry, the effect of thyroxine or thyroidectomy has been confined chiefly to problems of growth and egg production. In a previous paper (Kumaran and Turner, 1949) it was indicated that the gonadotrophic hormones of the anterior pituitary act upon homologous components of the gonads. One might expect that hypo- or hyperthyroidism would influence spermatogenesis and the secretion of the male hormone by the interstitial cells of Leydig as a result of the effect upon the gonadotrophic hormone secretion just as these hormones influence the maturation of the ovum and the hormone secretion of the ovary. There has been no suggestion that the thyroid hormone stimulates either spermatogenesis or male hormone secretion directly, i.e. has gonadotrophic hormone-like activity, but rather that in stimulating increased functional activity in either the male or . . .