The in vitro perifused rat ovary: II. Role of oxygen tension in the whole and quartered ovary

In vitro perifusion of whole ovaries raises questions about tissue viability and its effects on the observed ovarian steroid secretion. To assess effects of tissue degeneration, whole and quartered ovaries from pregnant mare serum gonadotropin (PMSG-) treated immature rats were perifused for 8 h, employing various levels of pO₂. Histological examination of both the whole and quartered ovary showed signs of degeneration in centrally located follicles but not in follicles located near the surface. However, basal and gonadotropin-stimulated (luteinizing hormone plus follicle stimulating hormone) secretion of estradiol, testosterone and progesterone were not significantly different in the whole ovary whether in the presence of high or low PO₂ (n=8; p > 0.05). Similarly, although the quartered ovary secreted greater amounts of steroids than did the whole ovaries (p < 0.05, n=8), pO₂ levels did not affect the steroid output. We conclude that during in vitro perifusion, minimal oxygen supply is sufficient for ovarian steroidogenesis to proceed. In addition, although quartered ovaries displayed some evidence of tissue degeneration, they were more responsive in terms of steroid output per mg ovary than were whole ovaries.