Abstract
To substantiate the assumption that the egg cell and blastomeres in planarian embryos influence surrounding yolk cells to form a syncytium, embryos at 1- to 8-cell stages were examined by electron microscopy. Within special areas of the endoplasmic reticulum both in the egg cell and in the blastomeres, a large number of vacuoles of various sizes formed and then disappeared at least four times over the period from egg-laying through the 8-cell stage as if their contents were being secreted. These activities diminished markedly at the 8-cell stage. Yolk cells surrounding the egg cell and blastomeres were aggregated in close contact with one another in a small clump shortly after egg-laying, and then, late in the 4-cell stage, became fused, forming a syncytium. The correlation between release of vacuoles by the egg cell and blastomeres and the formation of a syncytium by the yolk cells indicate that the cell fusion could be induced by a factor contained in the vacuoles.
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© 1991 Kluwer Academic Publishers
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Sakurai, T. (1991). An electron-microscopic study of syncytium formation during early embryonic development of the freshwater planarian Bdellocephala brunnea. In: Tyler, S. (eds) Turbellarian Biology. Developments in Hydrobiology 69, vol 69. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-2775-2_17
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DOI: https://doi.org/10.1007/978-94-011-2775-2_17
Publisher Name: Springer, Dordrecht
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