Koyanagi F, Nishiyama H
Cell Tissue Res. 1980;206(1):55-63. doi: 10.1007/BF00233607.
Spermatozoa with intact acrosomes, as well as those coming into contact with the ovum at a smaller angle, and morphologically abnormal spermatozoa reach the plasma membrane of the ovum via an extensively dissolved zone of the inner layer of the vitelline membrane. This zone is assumed to be formed by overlapping of two or more tunnels formed by spermatozoa that had previously come into contact with the ovum. When a spermtozoon comes into contact with the plasma membrane of the ovum, many cytoplasmic processes extend outwards and cover it. Thereafter, the plasma membranes of the processes fuse, thereby phagocytizing the spermatozoon. It is assumed that the he phagocytized spermatozoa cannot undergo transformation into male pronuclei and that they degenerate soon after phagocytosis.
顶体完整的精子，以及那些以较小角度与卵子接触的精子和形态异常的精子，通过卵黄膜内层广泛溶解的区域到达卵子的质膜。这个区域被认为是由先前与卵子接触的精子形成的两条或更多条隧道重叠形成的。当精子与卵子的质膜接触时，许多细胞质突起向外延伸并覆盖它。此后，突起的质膜融合，从而吞噬精子。据推测，被吞噬的精子不能转化为雄原核，并且在吞噬后不久就会退化。
