chorionic gonadotropin (CG) /kôr′ē·on″ik/ [Gk, chorion + gone, seed, trophe, nutrition] , a chemical component of the urine of pregnant women and pregnant mares. This glycoprotein hormone is secreted by the placental trophoblastic cells. It is composed of two subunits, alpha and beta, and helps maintain the corpus luteum during pregnancy. The alpha subunit is nearly identical to follicle-stimulating, luteinizing, and thyroid-stimulating hormones. The specific hormonal effects of chorionic gonadotropin are activated by the beta portion. They include stimulation of the corpus luteum to secrete estrogen and progesterone and to decrease lymphocyte activation. Chorionic gonadotropin is also administered in the treatment of some cases of cryptorchidism and male hypogonadism and in the induction of ovulation in some infertile women. Also called human chorionic gonadotropin. See also gonadotropin.
