Pathophysiology of anovulation.

Anovulatory disorders are physiological during puberty, postpartum period and just before the menopause. In pathology, they are one of the earliest symptoms of different diseases: functional or organic hypothalamic diseases, pituitary destruction or inappropriate feedback by the peripheral hormones and, obviously, primary ovarian insufficiency. Their real interest lies in their pathophysiology. Functional hypothalamic disorders are defined as the inability to liberate GnRH in a physiological way. The role of endogenous opioids, as essential factors of gonadotrophin regulation will be discussed. Hyperprolactinaemias, which represent 20% of the anovulations, have an antigonadotrophic effect at the hypothalamic level, but the very mechanism of the inhibitory effect of prolactin on GnRH is still open to discussion. Although polycystic ovarian disease is one of the most common endocrine abnormalities in women, its pathophysiology remains far from fully understood. The relative parts played by hypothalamic disturbances and by abnormal feedback of gonadal steroids will be discussed.