家兎受精卵の補足精子と極体の観察

抄録

Rabbit eggs from the 1-cell to the expanding blastocyst stage were examined for a study of the distribution of supplementary sperm and polar bodies. A total of 252 eggs was recovered from 37 does from 18 to 160 hours following mating; 237 of them were fertilized. Supplementary sperm persisted in 221 of the fertilized eggs (93.2%). Mean number of supplementary sperm in all fertilized eggs was 6.5-15.8, and of those recovered at 160 hrs post coitum was 3.2. Though the proportion of eggs with agglutinated supplementary sperm was over 50% in the 1-cell to the 16-cell eggs, the proportion significantly decreased after the 32-cell stage. Three polar bodies were observed in 27 eggs (19%) out of 142 during the 2-cell to the morula stage. Although the polar body was always located peripherally in the perivitelline space in the 2-cell stage, some eggs with one or two polar bodies located centrally among the blastomeres were found in both the 4-cell and the 8-cell stages in the present study. The same phenomenon was observed during in vitro culture of the 2-or the 4-cell stage eggs, also. It was noted that one to five sperm appeared in some blastocoelic cavities.