Improvement of meiotic competence of follicular oocytes by artificial techniques

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1. Improvement of meiotic competence of follicular oocytes by chemicalsOocytes of various sizes were isolated from ovaries by mechanical dissection using the gauge-needle and razor blade. This method yielded 26.2 7.4 growing and fully frown oocytes from an ovary. Cumulus-enclosed oocytes dissociated from the ovaries were cultured in vitro in a TCM 199 containing 10% fetal calf serum, none of the 90 m-diameter oocytes resumed meiosis. However germinal vesicle breakdown (GVDB) was observed in oocytes of which diameter exceeded 91 m. Polar body formation was observed in oocytes which have the diameter exceeding 101 m. About 80% of the 121 m-diameter oocytes were able to extrude the polar body. The percentage of oocytes with first polar body increased when incubated in the medium containing dibutyryl cyclic adenosine 3',5'-monophosphate in 101-to 120 m-diameter oocytes. These observations indicate that dibutyryl cyclic adenosine 3',5'-monophosphate can improve the meiotic competence of bov … More ine oocytes in culture.2. Prevention of soontaneous degeneration of mouse oocytes in culture by ovarian glycosaminoglycansMouse follicular oocytes cultured for more than 72 h in modified Krebs-Ringer solution in vitro undergo spontaneous segmentation to form "blastomeres" with or without unclear fragments or chromatin. Glycosaminoglycans(GAGs) isolated from bovine follicular fluid(bFF) and added to the suspending medium at concentrations of 0.25mg/ml or greater prevented the occurence of spontaneous segmentation in isolated cumulus-free mouse oocytes in a dose-dependent manner. The active material was isolated from bFF by chromatography on dowex 1-x2. The fraction eluted with 0.5 M NaCl plssessed the greatest biological activity. Preparations of purified bFF-GAGs and hyaluronic acid and chondroitin sulfate from a commercial soutce prevented the occurence of segmentation. Hyaluronic acid was more potent than chondroitin sulfate. The results indicate that GAGs prevent degeneration of oocyte in vitro. Less