EFFECT OF ALTERED THYROIDAL AND GONADAL ACTIVITY ON SIZE OF ENDOCRINE GLANDS AND RESISTANCE TO STRESS IN THE CHICK1,2

Abstract

Stress caused a marked adrenal enlargement, due to increase of both medullary and cortical tissue, which was generally unaffected by variations in thyroxine or gonadal hormone levels. This enlargement was indicative of but not necessarily allied with a successful resistance to stress. Since adrenal enlargement occurred in goitrous chicks exposed to stress, without concurrent gonadal atrophy, and in androgen-treated birds which were stressed, the pituitary does not necessarily shift its activity in response to increased demand for one of its hormones. Androgen increased the ability to resist stress somewhat more in females than in males. Untreated males resisted stress better than comparable females, and thyroprotein increased the resistance in both sexes.