전자저널 > 전자저널 > Ultrastructural Studies of Oocyte Differentiation and Vitellogenesis in female Phacosoma japonicus (Bivalvia: Veneridae) in Western Korea

Ultrastructural Studies of Oocyte Differentiation and Vitellogenesis in female Phacosoma japonicus (Bivalvia: Veneridae) in Western Korea

Je-Cheon Jun and Sung-Han Kim

West Sea Fisheries Research Institute, National Institute of Fisheries Science, Incheon 22383, Korea Faculty of Marine Applied Biosciences, Kunsan National University, Gunsan 54150, Korea

Ultrastructural studies of oocyte development and vitellogenesis associated with the follicle cells in female Phacosoma japonicus were investigated by electron microscope observations. Vitelloogenesis in the oocytes occured by way of endogenous autosynthesis and exogenous heterosynthesis: vitellogenesis occurred through a process of endogenous autosynthesis, which involves a combined activity of the Golgi complex, rough endoplasmic reticulum, and mitochondria. However, the process of exogenous heterosynthesis involved endocytotic incorporation of extraovarian precursors into the basal region of the early vitellogenic oocytes. In this study, follicle cells, which attached to the previtellogenic and vitellogenic oocytes, were easily found. In particular, the follicle cells were involved in the development of previtellogenic oocytes by the supply of nutrients, and vitellogenesis in the early and late vitellogenic oocytes by endocytosis of yolk precursors. The functions of follicle cells, which attached to mature oocytes, accumulate reserves of lipid granules and glycogen particles for vitellogesis in the cytoplasm of the follicle cells.

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