THE RECOVERY OF PREANTRAL FOLLICLES FROM OVARIES OF DOMESTIC CATS AND THEIR CHARACTERIZATION BEFORE AND AFTER CULTURE

The mechanical dissection of ovaries from domestic cats provided high numbers of preantral follicles (300-24 500 per ovary) with diameters of 40-90 mu m. The high variability between the individual queens was not correlated to age, cycle, breed or season. The number of primordial and primary follicles was significantly dependent upon the total recovery rate(r = 0.997; P < 0.0001). The growing population (secondary follicles) was relatively constant until the isolation rate dropped below 1000 per ovary. Then the number of growing follicles was correlated to the resting pool. Follicle viability, as estimated by trypan blue staining, dropped immediately after isolation to 32.5%. After 1 week of culture, follicle viability varied depending on the method of culture (in monolayer, 33.3%; co-culture with granulosa cells, 37.5%; in collagen gels, 30.8%; in conditioned medium, 9.3%; on agarose pad, 17.9%). A 10 mu m increase in diameter was observed in approximately 65% of growing follicles (61.3-68.6% depending on growth conditions). The number of surrounding granulosa cells decreased and 32% of the oocytes were without granulosa cells. The addition of epidermal growth factor (EGF) and insulin-transferrin-selenite (ITS) to the culture medium prevented these alterations in structure. In the control group only 22% of intrafollicular oocytes had an intact germinal vesicle as opposed to ITS-medium (57%) and EGF-medium viability.