Abstract
It was concluded from earlier investigations that the marked hypertrophy which results from implantation of the adrenal gland into the portal circulation in the rat depended upon a) the interposition of the liver and b) the presence of ovaries or estrogen. In the present investigation the marked hypertrophy of the implanted adrenal in the female, even when established for 5 months, rapidly regressed following oophorectomy. When estrogen was administered to the male rat as late as 6 months after implantation, the ordinarily nonhypertrophied implanted adrenal in this sex underwent extensive enlargement. The results of this investigation, together with our earlier findings, clearly demonstrate that estrogen is required not only for the initiation but also for the maintenance of the extensive hypertrophy which occurs in the adrenal implanted in the portal circulation. (Endocrinology74: 661, 1964)