Abstract
The authors are not aware of any literature which describes cytological or even histological changes in the anterior pituitary due to thyroid feeding or injections. That such changes should occur might be anticipated from reported structural changes in the pituitary following thyroidectomy 1 and also from the few reported instances of pituitary weight changes after thyroxin administration. Even these reports are contradictory. A further indication that structural changes may occur in such pituitaries is found in the reports that hyperthyroid rats show an increased sex-stimulating potency. 2 ,3 Weichert 4 demonstrated a prolonged dioestrus in rats after thyroid administrations, and in a subsequent work demonstrated prominent persistent functional corpora lutea. 5 All of these data refer to female rats. The present paper deals with cytological changes in the adult male rat and will be supplemented by a subsequent description of the female, which we now have reason to believe will show differences. The pituitaries of 36 adult albino male rats, purchased at Cambridge, England, which had been made hyperthyroid by injections of sodium thyroxin (British Drug House, London) or by feeding desiccated gland (Burroughs, Wellcome & Co. “Tabloids”), were studied. The thyroid tabloids were powdered on a glass plate and thoroughly mixed with a few cc. of thick, sweetened, condensed milk. The rats were observed until they finished eating the mixture, which they did avidly, and we believe that all of the thyroid was ingested. The manufacturers state that a tabloid has the equivalent of .324 gm. of fresh tissue. Each rat received one tabloid daily for 30 days. Those rats which were made hyperthyroid by injection received varying doses of from .028 to .28 mg. of sodium thyroxin daily for 30 days (Smelser).
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