OVARIAN TUMOURS IN MICE IN PARABIOTIC UNION

Abstract

Development of granulosal cell tumors of the ovary of mice requires prolonged ovarian stimulation by gonadotropin. Parabiotic union between a normal mouse and a castrated partner fulfills this, but produces hydro-nephrosis at an early age because of the excessive amts. of estrogen secreted by the overstimulated ovary. A 2d condition is, therefore, that ovarian secretion be blocked, or neutralized by transplanting the ovary into the portal system. This is only partly successful in parabiotic pairs, since the incidence of tumor is not increased over incidence in spleen-implanted ovaries in ordinary mice. If a 2d castrated mouse is used to form a parabiotic triplet, the single mouse with spleen-implanted ovary develops ovarian tumor early and uniformly, because the extra castrate mouse in the system effectively neutralizes any estrogen which escapes the liver of the 1st mouse, thus permitting the pituitary of the 2d castrate to continue to overstimulate the ovary. X-irradiation of the ovary produces even earlier tumors in association with parabiotic triplet-ovarian-spleen transplant system.