Cuasnicu P S, Bedford J M
Department of Obstetrics and Gynecology, Cornell University Medical College, New York.
Mol Reprod Dev. 1991 May;29(1):72-6. doi: 10.1002/mrd.1080290111.
In vitro fertilization techniques were used to analyze the penetrability of preovulatory hamster oocytes. The zonas of granulosa cell-free primary (GV) oocytes were penetrated in vitro in 2-3 h as readily as those of ovulated secondary oocytes (80% vs. 88%), whether inseminated separately or as mixed oocyte groups. In fact, a significantly higher (P less than 0.05) mean number of perivitelline spermatozoa was present in immature (3.6) compared with secondary (1.9) oocytes, primarily reflecting a lack of the zona block to polyspermy in the immature population. By contrast, when granulosa cells remained around GV oocytes, zona penetration was low and more were penetrated, with more spermatozoa incorporated into the vitellus as a function of increasing time of oocyte recovery after hCG. We conclude, contrary to previous reports, that the zona pellucida of the hamster GV oocyte is readily penetrable by spermatozoa in vitro. However, the resumption of meiosis brings an increase in the penetrability of the granulosa cell vestment as well as the capacity for cortical granule exocytosis and the ability to decondense and transform the fertilizing sperm nucleus. The fact that the zona pellucida of the immature oocyte has proved to be penetrable in vitro and/or in vivo in all the mammals studied in this respect is discussed with particular reference to the situation in man.
采用体外受精技术分析排卵前仓鼠卵母细胞的可穿透性。无论单独授精还是作为混合卵母细胞组授精，无颗粒细胞的初级（GV）卵母细胞的透明带在体外2 - 3小时内被穿透的情况与排卵后的次级卵母细胞一样容易（分别为80%和88%）。实际上，与次级卵母细胞（1.9个）相比，未成熟卵母细胞（3.6个）卵周间隙中的精子平均数显著更高（P < 0.05），这主要反映了未成熟卵母细胞群体中缺乏对多精受精的透明带阻断。相比之下，当颗粒细胞围绕在GV卵母细胞周围时，透明带穿透率较低，随着hCG后卵母细胞回收时间的增加，有更多的卵母细胞被穿透，且有更多精子进入卵黄。我们得出结论，与先前的报道相反，仓鼠GV卵母细胞的透明带在体外容易被精子穿透。然而，减数分裂的恢复会使颗粒细胞包膜的可穿透性增加，同时也会增加皮质颗粒胞吐的能力以及使受精精子核去浓缩和转化的能力。鉴于在这方面所研究的所有哺乳动物中，未成熟卵母细胞的透明带在体外和/或体内都已被证明是可穿透的，本文特别参照人类的情况对此进行了讨论。
