Sov J Dev Biol. 1975 Jul;5(4):300-8.
Eggs of the bivalve mollusks Ostrea gigas, Spisula sachalinensis, and Mactra sulcataria taken from the ovary and placed in sea water are capable of maturation: the nuclear membrane dissolves and polar body I is released. The percentage of such spontaneously ripening eggs differs widely in different females and apparently characterizes the degree of roe maturity. The fertilization rate of roe containing a small percentage of spontaneously maturing eggs increases considerably during holding in sea water and remains at a high level for several hours. Maximum percentage fertilization can be obtained only over a narrow range of sperm concentrations in suspension for the species studied. A concentration of 10-6 or 10-7 sperm/cm-3 is usually optimum; a decrease or increase in sperm concentration by an order of magnitude (in comparison with the optimum level) reduces percentage fertilization. It was shown that sperm in suspensions with concentrations above the optimum level are activated to a lesser extent and their speed of movement is less than at high dilutions.
取自卵巢并置于海水中的双壳贝类牡蛎、萨哈林岛斧蛤和沟纹马珂蛤的卵能够成熟：核膜溶解，第一极体释放。这种自发成熟卵的百分比在不同雌体中差异很大，显然表征了卵的成熟程度。含有少量自发成熟卵的卵在海水中保存时受精率显著提高，并在数小时内保持在较高水平。对于所研究的物种，只有在悬浮液中精子浓度的狭窄范围内才能获得最大受精百分比。通常10-6或10-7个精子/立方厘米的浓度是最佳的；精子浓度与最佳水平相比降低或升高一个数量级会降低受精百分比。结果表明，浓度高于最佳水平的悬浮液中的精子活化程度较低，其运动速度低于高稀释度时的速度。
