Pretreatment with follicle stimulating hormone promotes the numbers of human oocytes reaching metaphase II by in-vitro maturation

The objective of this study was to investigate the effect of folliclestimulating hormone (FSH) priming on the in-vitro maturation (IVM) of humanoocytes from healthy ovaries using a chemically defined culture system.Seventeen patients donating oocytes for research received a truncatedcourse of 600 IU FSH over 5 days and a further control group of ninepatients received no FSH treatment. Mid-follicular phase cumulus-enclosedoocytes (n = 160) were aspirated from follicles < or =4 mm diameterunder transvaginal ultrasound guidance and were cultured for 48 h inmicrodrops of medium containing 10 mIU/ml FSH and 100 mIU/ ml humanchorionic gonadotrophin (HCG). The results demonstrated that human oocyteswill efficiently undergo IVM under serum-free conditions. After mild FSHstimulation, a greater number of cumulus-enclosed oocytes was collected,and following culture, a lower rate of degeneration was observed.Significantly more oocytes completed nuclear maturation to metaphase IIfollowing FSH stimulation (71.1 versus 43.5%). In conclusion, a truncatedcourse of FSH stimulation in vivo improved the oocyte maturation rate invitro, giving a mean of 4.8+/- 0.7 metaphase II oocytes per patientcompared with only 2.1+/-0.7 from control patients, thus yielding moremature oocytes for future IVF treatment.