The effects of meiosis activating sterol on in-vitro maturation and fertilization of human oocytes from stimulated and unstimulated ovaries

The object of this study was to assess functional maturation in vitro by ob taining data on the fertilization and embryonic competence of human oocytes with or without exposure to meiosis activating sterol (MAS) during maturat ion in vitro. Immature oocytes were either collected from unstimulated pati ents with polycystic ovaries (PCO) during gynaecological surgery, or were d onated by patients undergoing a cycle of intracytoplasmic sperm injection ( ICSI) treatment including ovarian stimulation with gonadotrophins, PCO oocy tes had variable cumulus cover, which was retained during culture while tho se from ICSI patients were cultured without cumulus. The study included 119 oocytes from PCO patients and 72 from ICSI patients. The oocytes were allo wed to mature in vitro for up to 46 h in the presence or absence of MAS. Ma ture oocytes were inseminated by ICSI with fertile donor spermatozoa and em bryo development was monitored in vitro. MAS (30 mug/ml) significantly incr eased the survival of oocytes from PCO patients (P < 0.01) but did not sign ificantly affect the proportion completing maturation in vitro. For the ICS I patients, >90 % of oocytes survived in all culture groups, regardless of MAS addition, however MAS (10 or 30 mug/ml) significantly increased the pro portion of oocytes maturing in vitro (P < 0.05). The apparent tendency towa rds improved subsequent development in vitro will require larger numbers of oocytes for evaluation. Oocytes from ICSI patients matured more rapidly in vitro than those from PCO patients. Our results show positive effects of M AS on human oocytes, confirming previous data in mice. This work may have i mplications for the future clinical application of IVM.