牛卵母细胞体外成熟的研究

Studies on in Vitro Maturation of Bovine Oocytes

牛卵母细胞的成熟过程中，包括细胞膜、细胞质、细胞核的成熟。其中细胞质的成熟最为复杂。线粒体、皮质颗粒数量的变化和位移，脂滴类型的变化和形态改变，空泡形态学的变化等是鉴别卵母细胞幼稚、成熟和老化的重要特征。透明带随着培养而外侧疏松，内侧致密，卵母细胞膜上伸出的微绒毛为膨大泡状和细长毛状两种。在培养１４小时后颗粒细胞与透明带脱离联系。根据综合指标判定，１８小时之前为成熟生长期，１８～２６小时为成熟期，２６小时进入老化期．１８～２４小时为授精最佳时间。

bovine ovaries were recovered from the slaughterhouse. 867 Docytes of different categories were drawn from the follicles. in diameter of 2-6mm. The ultrastructure change during maturation were studyed by TEM. The ultrastructure of the oocytes matured in vitro andin vino was similiar. The maturatlon change included: (1) The number of conical gramclesincreased and the conical granules centrifugolly moved with maturation. Their generationwas cornelated with Golgi Comples. (2) Hooded Mitochondria decreased with maturationMitochondria moved to the conical area of the cytoplasm at 0-18 hour maturation stage.After 18-20 hours maturation, they moved again to the conical area and aggyegated underthe plasma membrane. (3) The lipid droplets had two types: full and half-full. The volumefraction and the diameter of lipid droplets decreased but the number of them increased withmaturation. (4) There were vesicles of all stages. The volume fraction and diameter decreased before 24 hours maturation stage, the volume fraction increased after 24hr stage.(5) A few granulosa cells linked to the oocytes with gap junction before maturation,andseperated completely at 14 hour stage. (6) The cumulus cells aged with maturation. (7) Thediameter, lenghth and density of microvilli hadn't significantly difference at different maturatlon stages.The start developmental stage of the oocytes from 2-6mm follicles was different, somewas very young but some had been aged. So, we thought that a good in vitro maturation system should have different maturation time to the oocytes at different developmental stage inorder to get higher maturation rate. The best stage for fertilization was 18-24br.