Abstract:The fertilization biology characteristics of eggs and sperms in two scallop species, Patinopecten yessoensis and Chlamys farreri, including morphological changes of gametes after release, egg water characteristics, sperm acrosome reaction, egg cortical reaction, and the effect of the sperm fractional separation components on the eggs, were observed using electronic microscopy, optical microscopy, and spectrum scanning analysis and insemination. The results showed that there were no significant difference in biological characteristics between P. yessoensis and C. farreri. No obvious appearance changes in the scallop sperms within 10min after release in the seawater. However, 30 minutes later, 25% of the sperms became head-enlarged to near spherical and the fertilization ability was weakened. While the fertilization ability of the scallop eggs did not change within 1 hour after release in the seawater, and about 33% of the eggs became cleaved but without appearance of polar body in two hours. Most egg cleavage were equal cleavage terminated at the 2-cell stage and some at the 4-cell stage, and the fertilization ability of the eggs at this phase were lost. Most sperms dropped into the egg water were autolyzed, and other sperm agglutinated. No intact sperm individual was seen after being transferred into the egg water for 10 minutes. The sperm acrosome reaction was induced by the egg water or calcium ionophone A23187.Although a few sperm heads attached to the surface of the eggs, the components of sperm including seminal plasma, sperm head, and sperm tail, could not activate the eggs. This research on biological characteristics of eggs and sperms in scallop are expected to provide basic data for understanding why sperm and eggs from different species of scallops could recognize each other and fertilize.
