Kalab P, Kopf G S, Schultz R M
Department of Biology, University of Pennsylvania, Philadelphia 19104.
Biol Reprod. 1991 Nov;45(5):783-7. doi: 10.1095/biolreprod45.5.783.
A precocious but limited loss of cortical granules (CG) occurs during mouse oocyte maturation both in vivo and in vitro. Although CG loss during maturation in vivo is not associated with changes in the zona pellucida (ZP), a maturation-associated conversion of ZP2 to ZP2f occurs during oocyte maturation in vitro in serum-free medium. We now demonstrate that a maturation-associated change of ZP3 to ZP3f, as assessed by a reduction in sperm binding, also occurs during maturation in vitro in serum-free medium, and that both newborn calf serum (NCS) and fetuin, each of which inhibits the ZP2 conversion, also inhibit the ZP3 conversion. The concentration-dependence of the NCS- and fetuin-mediated inhibition of the ZP2 conversion, coupled with the concentration of fetuin present in NCS, is consistent with fetuin being the component present in NCS that is primarily responsible for this inhibition. Although NCS can inhibit the ZP modifications that occur during oocyte maturation in vitro, ionophore treatment of eggs, which results in an extensive release of CGs over a short period of time, overcomes the inhibitory effect of NCS on the ZP2 conversion. Results of these studies suggest a potential regulatory function of serum-derived components in the formation of a fertilizable egg.
在体内和体外小鼠卵母细胞成熟过程中，都会出现早熟但有限的皮质颗粒（CG）丢失。虽然体内成熟过程中的CG丢失与透明带（ZP）的变化无关，但在无血清培养基中体外卵母细胞成熟过程中会发生与成熟相关的ZP2向ZP2f的转变。我们现在证明，通过精子结合减少评估，在无血清培养基中体外成熟过程中也会发生与成熟相关的ZP3向ZP3f的变化，并且新生牛血清（NCS）和胎球蛋白，这两种物质均可抑制ZP2转变，它们也抑制ZP3转变。NCS和胎球蛋白介导的对ZP2转变抑制的浓度依赖性，加上NCS中存在的胎球蛋白浓度，与胎球蛋白是NCS中主要负责这种抑制作用的成分一致。虽然NCS可以抑制体外卵母细胞成熟过程中发生的ZP修饰，但用离子载体处理卵子，会在短时间内导致CG大量释放，这克服了NCS对ZP2转变的抑制作用。这些研究结果表明血清来源成分在可受精卵形成中具有潜在的调节功能。
