A RE-EXAMINATION OF THE ANTIGONADAL EFFECT OF PROLACTIN IN THE MALE FOWL, <i>GALLUS DOMESTICUS</i>

Abstract

Injection of prolactin into adult cocks has been reported to decrease testis weight, tubule diameter and androgen production, resulting in decreased comb size and cessation of crowing (Nalbandov, 1945). Similar inhibitory effects of prolactin on the gonads were observed in male chicks (Breneman, 1942) and in laying and non-laying hens (Bates, Lahr &amp; Riddle, 1935). This antigonadal effect is thought to be produced by inhibition of pituitary FSH secretion, since injection of FSH with prolactin prevented gonadal regression (Nalbandov, 1945). There are a number of other species of birds in which antigonadal effects of prolactin have been described (see Meier &amp; Dusseau, 1968). Recent findings, however, indicate a complex interplay of hormones regulating gonadal growth and regression (Meier, Martin &amp; MacGregor, 1971) and there seem to be some avian species in which prolactin fails to inhibit