Changes at the Egg Surface during the First Maturation Division in the Spider Achaearanea japonica (Bos. et Str.)

概要

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Changes at the egg surface during the first maturation division were examined in the spider Achaearanea japonica under the light and electron microscope. Newly laid eggs had already accepted a sperm nucleus. The nuclear division of the primary oocyte had occurred parallel to the egg surface and then the meiotic spindle developed perpendicular to the egg surface to complete the division. The cell membrane began to invaginate from the egg surface immediately after oviposition. Then the lumen of the invagination became wider and the large yolk granules became organized into an outer columnar layer and an inner spherical mass. The outer layer of the "vitelline membrane" appeared to be formed by the contents of periplasmic granules, which were newly detected in the present study. These granules discharged their contents by exocytosis. The formation of the outer layer after entrance of the sperm nucleus suggests that the "vitelline membrane" of the spider egg is equivalent to a fertilization membrane and is not a true vitelline membrane.
社団法人日本動物学会の論文
1994-10-15