The Second Maturation Division and Fertilization in the Spider Achaearanea japonica (Bos. et Str.)

概要

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Formation of the main layer of the vitelline membrane, the second maturation division and fertilization were examined in the spider Achaearanea japonica by light and electron microscopy. Newly laid eggs had already accepted a sperm nucleus near the periphery . The sperm nucleus was observed as a mass of condensed chromatin, which was not enclosed by a nuclear envelope. Bundles of microtubules, which separated the large yolk granules that surrounded the perinuclear cytoplasm into radial arrays immediately after oviposition, seem likely to play an important role in the migration of the sperm nucleus together with perinulclear cytoplasm to the center of the egg. The matrix that was released from the vesicles, by exocytosis , into the space between the cell membrane and the outer layer of the vitelline membrane appeared to form the main layer of the vitelline membrane. The second maturation division of the first polar body progressed to telophase , but daughter nuclei were not formed. The maturation division of the secondary oocyte was strictly synchronized with respect to that of first polar body, and it generated the female pronucleus and the nucleus of the second polar body. The female pronucleus moved toward the egg's center, in which the male pronucleus was now located, for conjugation. The larger pronucleus was probably the male pronucleus, and the other one was probably the female pronucleus.
社団法人日本動物学会の論文
1994-06-15