A hormone produced by the Sertoli cells of the testes in a male embryo to suppress the development of the Mullerian ducts.

(pronounced 'mool-air-ian') Syn. paramesonephric duct. The internal female sex duct, which forms on each side of a female embryo to connect the peritoneal cavity with the outside of the embryo, starting at a point close to the ovary and forming first a fallopian tube then meeting its fellow from the other side to form the uterus, and then extending downwards to form the upper part of the vagina before finally connecting with a little dimple between the urethra (in front) and the anus (behind) to reach the exterior at the vulva. Passage of eggs from the ovaries (which ovulate into the peritoneal cavity of all vertebrate species) to the outside world through this duct is how animals, including humans, reproduce. In males the ducts do not develop because the Sertoli cells of the testes produce anti-Mullerian hormone.

Cells in the testis lining the testicular tubules that nurture the developing sperm cells; responsible in fetal life for the production of anti-Mullerian hormone, which stops the male fetus from developing fallopian tubes, a uterus and a vagina. A source of estradiol in men.

A state of intersex in which the karyotype is male (i.e. 46,XY), the gonads are testes (hence also male), but the body is completely unresponsive to testosterone and to its metabolite dihydrotestosterone, so it develops in the female way, with a normal vulva and vagina apparent at birth, and with normal development of the breasts at puberty. Because the testes still secrete anti-Mullerian hormone, there's no uterus. Invariably these children are raised as girls, normal except for their primary amenorrhea and their infertility. Specialist medical supervision is needed, because there is an increased risk of cancer in the abnormal gonads. Synonymous with androgen insensitivity syndrome (complete form).

The womb, in which pregnancy is gestated from the time of implantation of the embryo until delivery or miscarriage; formed from the joining of the two Mullerian ducts (in the absence of anti-Mullerian hormone); composed of the main, upper part (the uterine fundus) and a lower neck, or cervix, which connects it to the upper part of the vagina; most of its wall is made of muscle tissue (the myometrium), but with an inner lining of glands (the endometrium) and, on the outer surface, a thin covering of uterine serosa. Best seen on transvaginal ultrasound, especially a three-dimensional ultrasound; its cavity is best displayed with a hysterosalpingogram (or, strictly, a hysterogram).