メダカ卵における第一割面と胚軸について

概要

論文の詳細を見る
The close relationship of the first cleavage plane and embryonic axis to the morphological characteristics of the madaka egg was examined in a preliminary study. In unfertilized eggs the meiotic figure was found in the vicinity of a cluster of minute oil droplets, which were distributed around the germinal vesicle in immature oocytes. Just after exocytosis of cortical alveoli was initiated by insemination, the positions of the microplye and the cluster of minute oil droplets presenting the position of the meiotic figure were marked by inserting spinules from a cactus into the egg equatorial of these structures. The majority (79%) of 99 eggs formed a first cleavage plane approvimately coinciding with the axis connecting the spinules (M-M axis). On the other hand, when the spinules were inserted at right angles to the M-M axis, a similar result was obtained. These results suggest that the M-M axis may serve as a reliable marker of the first cleavage plane. In addition, it was observed that the axis of the embryonic body formed at an angle 61°-90° to the M-M axis in 63% of the eggs (19) examined.
1993-02-10