Leukocyte supplementation increases the luteinizing hormone-induced ovulation rate in the in vitro-perfused rat ovary.

Ovaries from eCG-primed (20 IU s.c. on Day 28) rats were perfused from the morning of Day 30 of age in a recirculating system initially containing a buffered blood cell-free medium (M199 + 4% BSA) for periods of up to 21 h. The addition of ovine LH (0.1 micrograms/ml) at 0 h of perfusion resulted in ovulations in all 6 ovaries perfused (3.2 +/- 0.7 ovulations per treated ovary; mean +/- SEM), whereas none of the 6 control ovaries ovulated. Rat leukocytes (50 x 10(6)), added at 7 h of perfusion significantly increased the number of LH-induced ovulations (7.8 +/- 0.5; p less than 0.05). All ovulated oocytes showed resumption of meiosis as judged from the presence of germinal vesicle breakdown. Ovaries perfused with leukocytes but without LH did not ovulate. Histological examination of ovaries 14 h after leukocyte administration showed a considerable number of perifollicular extravasated white blood cells. These findings indicate that leukocytes participate in the normal ovulatory process as part of an inflammation-like reaction.