鋏角類の卵形成様式について

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概要

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• The oogenetic mode in chelicerates has not yet been generalized enough to be compared with that in mandibulates. Various oogenetic processes of some chelicerates, such as horseshoe crab, scorpions, uropygids, araneids, opolopns, ticks and pseudoscorpions, have been compared and generalized into a basic ovarian structure and a common oogenetic pattern. The basic form of the chelicerate ovary is a simple tube, bent into a loop, connected with the paired oviducts at the both ends. This looped tubular ovary has no terminal germ zone seen in the ovariole of mandibulates. The germ zome of chekicerates lies in the ovarian epithelium along the ventro-median line of the tubular ovary as a cord-shaped germarium. Simple ovaries most similar to the basic form have been seen in ticks and opilions. Eggs are formed at any region of the ovary. Oogonia and early previtellogenic oocytes stay in the germarium. Growing previtellogenic oocytes, however, migrate outwards from the germarium raising the basement membrane of the ovarian epithelium. Finally they protrede out of the ovarian tube into the haemocoel, surrounded by the expanded basement membrane and accompnied by the epithelial egg-stalks. Vitellogenesis takes place only in such staiked oocytes without any help of the auxiliary cells. Mature eggs are ovulated into the ovarian lumen through the stalk-cavity. The oogenetic mode of chelicerates seems much different from that of mandibulates especially in localization of germarium and vitellogenic oocytes.節足動物の卵形成様式は大顎類（特に昆虫類）でよく調べられ、模式化されて理解されている。すなわち、昆虫類の卵巣の単位構造である卵巣小管は conical な管状で、一端は細く盲端に終り、他端は太く輸卵管につながる。形式細胞巣は細い盲端部に局在し、若い卵母細胞はここから卵巣小管の内腔中に出てくる。・・・

• 筑波大学の論文

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