Ovarian thecal metaplasia in adrenal glands.

Wedge-shaped microscopic nodules resembling ovarian stroma or theca were found in the adrenal cortices of 14 women. Thirteen of the women were postmenopausal and one had ovarian stromal hyperplasia. The lesions were frequently multiple and bilateral and were almost always located just beneath the adrenal capsule. These nodules probably represent metaplasia of embryologically competent cells in the adrenal cortex or capsule which become transformed into ovarian tissue under the influence of unopposed pituitary gonadotropin during or after menopause. Support for this theory is found in (1) studies of human embryos that demonstrate the intimate anatomic development of ovary and adrenal gland, (2) experimental studies of mice that had morphologically similar, functional adrenal nodules following bilateral oophorectomy at birth, and (3) reports of certain human adrenal tumors. It is not known whether these nodules have functional significance in the human female.