Müllerian Inhibiting Substance

Definition

MIS; the factor secreted by the sertoli cells of the embryonic developing testis that causes regression of the Müllerian ducts, the primordia for the accessory sex glands of the female. In mammals, MIS prevents the development of the Mullerian ducts into the uterus and other Mullerian structures. The effect is ipsilateral, that is each testis suppresses Müllerian development only on its own side. In humans, this action takes place during the first 8 weeks of gestation. If no hormone is produced from the gonads, the Mullerian ducts automatically develop, while the Wolffian ducts, which are responsible for male reproductive ducts, automatically die. Amounts of MIS that are measurable in the blood vary by age and sex. MIS works by interacting with specific receptors on the surfaces of the cells of target tissues. The best-known and most specific effect, mediated through the MIS type II receptors, includes programmed cell death (Apoptosis) of the target tissue (the fetal...