牛体外受精的程序及超微结构研究

牛体外成熟卵母细胞体外受精后３小时精子入卵，８小时原核形成，２４小时的核多到卵中央。精子发生顶体反应的部位主要在透明表面，方式是顶体外膜自身囊经，发生顶体反应的粗子可斜向或垂直穿过透明带。卵丘细胞可吞噬大量精子，在阻多精受精中发挥重要作用。高尔基得合体，线料体、环状片层和滑面内质网等在原核周围形成细胞器集团。牛体外受精卵的雌雄原结合比体内受精的要延迟，胞吐到卵周隙中的皮质颗粒内容物扩散不完全。

PROCESS AND ULTRASTRUCTURE OF BOVINE IN VITRO FERTILIZATION

The events occurred and the ultrastructure of in vitro matured bovine oocytes at different times postinsemination (1. 5h, 3h, 5h, 8h, 13h, 18h, 24h) were studied with trans- mission electron microscopy. Sperm penetration and male pronucleus (mPN) formation occurred at 3h and 8h postinsemination, respectively. With its gradual volume expansion, the mPN moved to the center of the ooplasm at 24h postinsemination. The same event might occur at different times in different oocytes. Although the cumulus cells might induce acrosome reaction (AR) in some spermatozoa, it seemed that AR occurred in the manner of vesiculation of outer acrosomal membrane itself on the surface of ZP. The acrosome-reacted spermatozoa went through the ZP obliquely or perpendicularly. The cumulus cells could engulf many spermatozoa, which might play an important role in polyspermy prevention. The main differences between the first polar body and the second polar body was that the former contained many conical granules (CGS) and other organelles, but the later did not. There were many polymorphological hooded mitochondria, smooth endoplasmic reticulum (SER) and vesicles distributed evenly in the zygote cytoplasm. Developed Golgi complexes, rich polymorphological hooded mitochondria, annulate lamellae and SER formed an organelle cluster around the pronucleus. Several Compacted nucleoli existed in the pronucleus. The main deviations of bovine in vitro fertilization were the delay of syngamy and the incomplete dispersion of CGS contents in the perivitelline space.