Electron Microscopic Observation of Chorion Formation in the Teleost, Navodon modestus(Developmental Biology)

概要

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The chorion of the mature egg of the black scraper, Navodon modestus, is composed of an outer and an inner layer. The outer layer of the chorion has two distinct sublayers; the outer part is thicker and the inner part has a higher electron density. The inner layer is composed of concentric strata; the distance between these strata decreases towards the outer border. Chorion formation begins from the outer part of the outer layer, proceeding through to the inner part of the outer layer and then into the inner layer. However, the outer part of the outer layer continues its formation progressively with its thickness increasing until the formation of the inner layer is completed. The pit on the surface of the chorion is an interspace through which a microvillus passes, appearing at an early stage of the chorion formation. During the process of chorion formation, the oocyte has to increase successively the thickness and surface area of the chorion as it grows. The consequent increase of the surface area of the chorion is roughly estimated as ll- to 14-fold. The number of pits in the chorion, however, does not increase during the process of growth.
社団法人日本動物学会の論文
1985-08-15