| dc.description.abstract |
Early antral follicles 0·5-0·7 mm in diameter weredissected from bovine ovaries, and oocyte-cumulus complexes with piecesof parietal granulosa (OCCGs) were then collected from the follicles. TheOCCGs containing oocytes of 90-99 m diameter (94·7 ±2·8 µm, n = 196) were selected andembedded in collagen gels and cultured for 14 days in TCM199 containing10% fetal calf serum and 4 mM hypoxanthine. From cultured OCCGs, 144surviving oocytes were recovered, of which 53 were granulosa cell-enclosedoocytes and 91 were denuded oocytes. The mean diameter of the survivingoocytes was 114·2 ± 8·4 µm, significantly largerthan that measured before culture (P < 0·05).The granulosa cell-enclosed oocytes and denuded oocytes were further culturedfor maturation for 24 h. After culture, 72% (38/53) of thegranulosa cell-enclosed oocytes and 59% (54/91) of the denudedoocytes showed normal morphology. These oocytes were then inseminated withbovine spermatozoa. After 29 h of insemination, all of the denuded oocytes haddegenerated, while 32% (12/38) of the granulosa cell-enclosedoocytes showed normal morphology. Of the 12 oocytes, 5 were penetrated byspermatozoa, and 2 formed both male and female pronuclei. These resultsdemonstrate for the first time that bovine oocytes grownin vitro acquire meiotic competence and can bepenetrated by spermatozoa. |
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