When oocytes were cultured in intact antral follicles for various time periods, it was shown that shorter periods (24 and 48 h) resulted in significantly higher rates of GV arrest and subsequent maturation than for follicles maintained for longer periods. In addition, during prolonged follicle culture, oocytes resumed meiosis within the follicle. The reasons for this are presently unknown; however, one possibility is that the follicles themselves may degenerate, releasing the oocytes from the inhibitory effects of follicular components, allowing the resumption of meiosis. Figure 6 shows an example of an oocyte with expanded cumulus layers following culture within an intact follicle for 3 days. In these experiments there was no supplementation of the culture medium with specific hormones or growth factors that have previously been reported to be necessary for follicular viability and growth in vivo, i.e., gonadotropins, estradiol, insulin-like growth factor-1, epidermal growth factor, or basic fibroblast growth factor. buy asthma inhaler
The data presented here suggest that the culture of intact bovine antral follicles is an efficient method for the maintenance of meiotic arrest for at least 24 h. In addition, oocytes derived after 24 h of antral follicle culture have significantly higher developmental competence than oocytes aspirated directly from follicles 3-8 mm in diameter. This suggests that during the culture period, follicle-enclosed oocytes acquire a greater developmental competence. However, when the proportion of the oocytes that developed to the blastocyst stage was calculated, there were no significant differences between the two groups (24% vs. 26%). This observation is in agreement with recently published data demonstrating that oocytes acquire developmental competence prior to maturation.