1990 年 56 巻 3 号 p. 425-430
The events of meiosis and fertilization in Japanese pearl oyster eggs allowed to develop at dif-ferent temperatures (18°C, 23°C, and 28°C) were investigated with fluorescence microscope. Change of matemal and paternal chromatin of eggs at 23°C were as follows. Spawned eggs were at metaphase of first meiosis. Subsequent to sperm penetration most eggs completed first and second meiosis by 15 and 24 min after insemination, respectively. Female and male pronuclei were formed by 30 min after insemination. The chromatin of male and female pronuclei con-densed gradually and were finally observed as two groups of chromosomes. The two groups of chromosomes combined and formed on the metaphas plate for first cleavage. By 62 min most eggs completed first cleavage.
It was observed at the higher temperature, that the eggs developed faster. Percentages of eggs which showed abnormal chromosome behavior were higher at 18°C and 28°C than at 23°C. Asynchronous development of eggs was observed in all temperature groups. Asynchrony of eggs development was more apparend at 18°C.