A. A. Reunov, A. V. Akhmadieva, Ya. N. Aleksandrova, A. V. Komkova, K. V. Aleksandrova - Formation of germinal granules in oocytes of a holothurian Apostichopus japonicus (Selenka, 1867) (Echinodermata: Holothuroidea)

BIOLOGIYA MORYA, 2015, Vol. 41, No. 1, pp. 72-75

Formation of germinal granules in oocytes of a holothurian Apostichopus japonicus (Selenka, 1867) (Echinodermata: Holothuroidea)

A.V. Zhirmunsky Institute of Marine Biology, Far East Branch, Russian Academy of Sciences, Vladivostok 690041

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Formation of germinal granules during oogenesis was studied in sea cucumbers Apostichopus japonicus, Selenka, 1867, by using transmission electron microscopy. It was found that in the early oogenesis mitochondria interact with the Balbiani body, gradually become immersed into its substance and transformed into electron-dense structures, which are similar to germinal granules of metazoans. In the late oogenesis, formed germinal granules lose their contacts with the Balbiani body and are localized in the cortical portion of oocyte, near the cell membrane. Vestigial mitochondrial cristae are a typical feature of germinal granules. The obtained data allow us to suggest that the process of transformation of mitochondria into germinal granules is one of Balbiani body's functions, the role of which still remains unexplained.

Key words: Holothuria, oogenesis, mitochondria, germinal granules, Balbiani body, electron microscopy.