Reaction of Anterior Hypophysis of Immature Rat to Placental Hormones. ∗

Abstract

Lehmann 1 has reported that injection of placental extracts brings about pregnancy changes in the anterior hypophysis of the female rat. Collip and his associates 2 have recently reported that long term injection of the anterior-pituitary-like hormone of the placenta brings about an enlargement of the anterior hypophysis, which is later followed by a decrease.

We have carried out a series of experiments in which we have studied the histological changes in the anterior pituitaries of immature rats which had received injections of a relatively crude oestrin-free extract of placenta. The method of preparation of this extract has been described. 3 We have used litters of immature female rats, 25 to 35 days old. Half of the animals in each litter received 2 subcutaneous injections daily for 6 to 8 days. The remaining animals in the litter served as controls.

The results of the injections were constant and definite. Table I illustrates some of our findings and shows that the ovaries of the injected animals were markedly increased in size.† The swollen and hyperemic pituitaries of the injected animals exhibited a moderate but invariable weight increase when compared with those of the controls. The ovaries and pituitaries of all animals were weighed on a torsion balance accurate to 0.5 mg. (Hartmann and Braun). Analysis of Table I reveals that the increase in the size of the hypophysis was as a rule greatest in the animals in which the ovarian reaction was greatest, a fact already noted by Collip and associates.

Complete serial sections of the hypophyses of both the control and experimental animals were cut. One section from each ribbon of 25 was mounted, giving a complete set of sections. Every fifth or sixth slide of each set of sections was studied.