Histological Effects of 11-Ketotestosterone, 17α-Methyltestosterone, Estradiol, Estradiol Cypionate, and Cortisol on the Interrenal Tissue, Thyroid Gland, and Pituitary Gland of Gonadectomized Sockeye Salmon (Oncorhynchus nerka)

Effects of two androgens, two estrogens, and cortisol in gonadectomized sockeye salmon (Oncorhynchus nerka) were investigated. Males were injected with 11-ketotestosterone, 17α-methyltestosterone, or cortisol for 4 or 7 weeks. Females were injected with estradiol, estradiol cypionate, or cortisol for 8 weeks.Both the androgens and the estrogens caused interrenal hypertrophy. The effect of 17α-methyltestosterone was stronger than that of 11-ketotestosterone, and of the two estrogens used, estradiol cypionate exerted the most marked effect. Cortisol brought about a slight atrophy of the interrenal tissue.A pronounced histological activation of the small thyroid follicles was induced by the two androgens. The estrogens exerted no visible effect on the thyroid gland, and cortisol treatment caused a slight reduction in the height of the follicular epithelium.In the gonadectomized control fish of both sexes, gonadotrophs were small and practically all devoid of granules. All four sex steroids induced the appear...