The characterization of granular amoebocytes and their possible roles in the asexual reproduction of the polystyelid ascidian, Polyzoa vesiculiphora

Authors

  • Hirokazu Fujimoto,

    1. Institute of Zoology, Faculty of Science, Tokyo Kyoiku University, Otsuka, Tokyo, Japan
    2. Shimoda Marine Biological Station, Tokyo Kyoiku University, Shimoda, Japan
    Current affiliation:
    1. Laboratory of Cell Biology, Mitsubishi-kasei Institute of Life Sciences, Minamiooya, 11, Machida-shi, Tokyo, 194, Japan
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  • Hiroshi Watanabe

    1. Institute of Zoology, Faculty of Science, Tokyo Kyoiku University, Otsuka, Tokyo, Japan
    2. Shimoda Marine Biological Station, Tokyo Kyoiku University, Shimoda, Japan
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  • Contributions from the Shimoda Marine Biological Station No. 301.

  • The cost of this research has been partly defrayed from the Scientific Research Expenditures of the Department of Education of Japan and the Asahi Press.

Abstract

The blood cells in the bud and the zooid of the polystyelid ascidian, Polyzoa vesiculiphora, were examined by means of light and electron microscopy to identify the cells that have been named trophocytes. The large blood cells were abundant in the mesenchymal space of the bud, but not in that of the functional zooid. They contained glycogen particles, lipid droplets, large protein granules and autophagosomes in their cytoplasm and were identified as granular amoebocytes. The majority of these cells were specifically phagocytized by phagocytes during bud development and disappeared. These results indicate that the granular amoebocytes virtually represent trophocytes in Polyzoa and may participate in bud development via nutrient supply to the developing tissues.

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