Okada A, Inomata K, Nagae T
Second Department of Anatomy, Toho University School of Medicine, Tokyo, Japan.
Anat Rec. 1993 Dec;237(4):518-26. doi: 10.1002/ar.1092370412.
Exocytosis of cortical granules (CGs) and the concomitant electron density changes of the zona pellucida (ZP) in the absence of sperm penetration were investigated in mouse oocytes processed with tannic acid containing fixation at various stages during and after maturation. After fusion of the CG membrane with the plasma membrane, the CG contents became very electron-dense, due to tannic acid. CG material is seen to be made up of coarse granular structures which gradually change to fine amorphous structures, which accumulate within the developing perivitelline space (PVS). When the coarse CG material attaches to the ZP, small domains exhibiting higher electron density appeared, and the number of these domains gradually increased. Release of CG was observed from metaphase I through metaphase II. In metaphase I to immediately after ovulation, the higher electron density of ZP and CG release was restricted to the cortical area overlying the meiotic spindle. Finally, the CG-free domain formed itself overlying the meiotic spindle as a result of CG release. However, in oviductal ova, CG release additionally occurred in the hemisphere opposite the spindle. At this stage the entire PVS was well developed and contained numerous fine electron-dense materials. Moreover, the inner half of the ZP increased in electron density as well. This change in electron density of the ZP might be associated with released CG material. These results suggest that the "partial cortical reaction" may play an important role in conditioning the ZP prior to ZP reaction.
在成熟过程中和成熟后不同阶段，用含单宁酸的固定剂处理小鼠卵母细胞，研究在无精子穿透情况下皮质颗粒（CGs）的胞吐作用以及透明带（ZP）伴随的电子密度变化。CG膜与质膜融合后，由于单宁酸的作用，CG内容物变得电子密度非常高。可见CG物质由粗颗粒结构组成，这些结构逐渐变为细无定形结构，并在发育中的卵周隙（PVS）内积聚。当粗的CG物质附着到ZP上时，出现了电子密度较高的小区域，且这些区域的数量逐渐增加。观察到从减数分裂中期I到减数分裂中期II都有CG释放。在减数分裂中期I到排卵后即刻，ZP较高的电子密度和CG释放局限于覆盖减数分裂纺锤体的皮质区域。最后，由于CG释放，在减数分裂纺锤体上方形成了无CG区域。然而，在输卵管中的卵子中，CG释放还发生在与纺锤体相对的半球。在此阶段，整个PVS发育良好，含有许多细小的电子致密物质。此外，ZP的内半部电子密度也增加。ZP电子密度的这种变化可能与释放的CG物质有关。这些结果表明，“部分皮质反应”可能在ZP反应之前对ZP进行预处理中起重要作用。
