Human ovaries contain immunoreactive oxytocin.

Ovarian tissues (n = 26) obtained at surgery were assayed for oxytocin (OT) concentrations in different parts of the ovary by a specific and sensitive RIA after homogenization and extraction with 0.4 M acetic acid. Chromatography of the extract on a Sephadex G-25 column revealed a single peak identical to synthetic OT, as measured by RIA. Corpora lutea of the menstrual cycle had 10.8-53.0 ng immunoreactive OT/g tissue (n = 7), while those of early pregnancy had a concentration of 106.0 ng/g (n = 1). Ovarian stromal tissue had either undetectable or lower concentrations of OT (0-21.0 ng/g; n = 5) than the corpus luteum from the same ovary. While a luteoma of term pregnancy (n = 1), a benign cystadenoma (n = 2), and an endometriotic cyst (n = 1) had no detectable immunoreactive OT, the concentrations of immunoreactive OT were 20.0 ng/g in a thecoma, 1.4, 20.0, and 60.0 ng/g in preovulatory follicles (n = 3), and 41.0 and 37.0 ng/g in polycystic ovaries (n = 2). In one patient with premature ovarian failure, the ovaries had 9.0 ng/g and undetectable immunoreactive OT. These findings indicate the presence of immunoreactive OT in human ovaries, with significant concentrations in the corpus luteum and preovulatory follicles. It is probable that these tissues produce OTs or an OT-like material which may function as an ovarian luteolytic agent.