Response of Chick Testes and Ovaries to Rat Pituitary Implants. ∗

Implants of rat pituitaries were made into 98 male and 40 female chicks as part of a program of study of the pituitary-gonad inter-relationship. The results were unexpected, and we believe of general interest because of possible bearing on the problem of species specificity of hormone action. The bird affords an excellent test for experiments involving pituitary hormones of animals in different classes because: (1) of the marked response of the immature testis to the “follicle stimulating’ hormone (F.S.H.), 1 and, (2) since it was reported by one of us, 2 that the testes of chicks given the pituitary luteinizing principle differed histologically from those of chicks which received F.S.H.

Young adult rats weighing 180225 gm. were used as donors and those castrated were operated upon 9 weeks previous to the time of implantation, Weights of pituitaries used corresponded closely to those tabulated for Wistar rats of similar weight. 3 Single pituitaries were implanted subcutaneously into the chicks on the 5th and 7th days after hatching and the birds were killed on the 9th day. Control experiments with implants into immature female rats demonstrated the same quantitative difference in ovarian weights which has been reported by other workers. 4 A summary of the results in the chick appears in Table I.

These data indicate quite definitely that the increased weight observed for the testes and ovaries did not demonstrate the striking differential weight increment found when immature female rats were recipients of implants. There was moreover, no statistically significant difference between the averages of the various male or female groups. In contrast to the rat, the heaviest gonads occurred in cockerels which were given pituitary implants from normal females.