Ant. Pituitary Changes in the Adult Male Rat Following Thyroidectomy. ∗

Abstract

The authors, in the preceding paper, have reported changes in the anterior pituitary of the adult male rat following administration of thyroid. The present paper deals with the changes which occur after thyroidectomy.

The literature is replete with descriptions of pituitary changes following thyroidectomy. Numerous workers have reported that hypertrophy of the pituitary follows ablation of the thyroid. Simpson and Hunter 1 and Marine 2 review these findings, and Hammett 3 has confirmed them. The effect of thyroidectomy upon the gonad-stimulating potency of the pituitary has also received attention. Smith and Engle 4 and Van Horn 5 found no change in this potency although Evans and Simpson 6 reported a decrease. Histological studies of the pituitary after thyroidectomy have also been numerous. Trautmann, 7 in his admirable treatise on pituitary changes in the goat, fully reviews previous literature. Bryant 8 described in the rabbit a decrease in eosinophiles and a degenerated vacuolated hypertrophy of the chromophobes indicating a state of decreased secretion, while Kojima 9 reported that thyroidectomy, like castration, results in an increase in basophiles in the anterior pituitary of the rat, some of which are colloid filled.

The pituitaries of 9 thyroidectomized adult male rats of the Long-Evans strain were reserved for cytological study. The pituitaries were fixed, sectioned serially at 3/u, and stained as described in the preceding paper. The larynx region was removed at autopsy and carefully examined with a dissecting scope for thyroid tissue, and, although in no instance was any found, the material was preserved for serial sectioning.