Summary
Ultrastructural studies on sperm-egg interaction at the time of fertilization inLaternula limicola were performed. The “temporary-acrosome” did not change morphologically while the sperm passed through the egg investments. At the onset of sperm entrance into the egg, however, the temporary-acrosome and mitochondria were eliminated from the sperm. Afterwards the sperm was engulfed by the egg surface without membrane fusion of the gametes. After entry the sperm nucleus was surrounded by four membranes: the plasma membranes of the egg and of the sperm, and the membranes of the sperm nuclear envelope. As the sperm nucleus differentiated into the male pronucleus, the plasma membranes of both the sperm and egg were initially vesiculated, then dispersed into the egg cytoplasm. Finally, the sperm nuclear envelope changed into the male pronuclear membrane accompanying sperm chromatin dispersion.
Similar content being viewed by others
References
Dan, J. C., 1952: Studies on the acrosome. 1. Reaction to egg-water and other stimuli. Biol. Bull.103, 54–66.
Franklin, L., 1965: Morphology of gamete membrane fusion and of sperm entry into oocytes of the sea urchin. J. Cell Biol.25, 81–100.
Hylander, B. L., Summers, R. G., 1977: Ultrastructural analysis of the gametes and early fertilization in two bivalve molluscaChama mecerophylla andSpisula solidissima with special reference to gamete binding. Cell Tiss. Res.182, 469–489.
Iwamatsu, T., Ohta, T., 1978: Electron microscopic observation on sperm penetration and pronuclear formation in the fish egg. J. exp. Zool.205, 157–180.
Kubo, M., 1977: The formation of a temporary-acrosome in the spermatozoon ofLaternula limicola (Bivalve, Mollusca). J. Ultrastruct. Res.61, 140–148.
Longo, F. J., 1973: An ultrastructural analysis of polyspermy in the surf clam,Spisula solidissima. J. exp. Zool.183, 153–180.
Popham, J. D., 1975: The fine structure of the oocyte ofBankia australis (Teredinidae, bivalvia) before and after fertilization. Cell Tiss. Res.157, 521–534.
Villa, L., 1977: An ultrastructural investigation on preliminaries in fertilization ofAscidia malaca (Urochordata). Acta Embryol. Exp.2, 179–193.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kubo, M., Ishikawa, M. & Numakunai, T. Ultrastructural studies on early events in fertilization of the bivalveLaternula limicola . Protoplasma 100, 73–83 (1979). https://doi.org/10.1007/BF01276302
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01276302