Ishijima S, Ishijima S A, Afzelius B A
Biological Laboratory, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo, Japan.sishijim@ bio.titech.ac.jp
Cell Motil Cytoskeleton. 1999 Oct;44(2):85-95. doi: 10.1002/(SICI)1097-0169(199910)44:2<85::AID-CM1>3.0.CO;2-#.
The marine snail, Turritella communis, produces two types of spermatozoa, named apyrene and eupyrene. Eupyrene spermatozoa are usually paired, but unpaired ones are involved in fertilization. Movements of these spermatozoa were analyzed using a video camera with a high-speed shutter. The eupyrene spermatozoa usually swim with the head foremost but are able to swim flagellum foremost. A reversal of the direction of their swimming was found to be the result of a change in the direction of flagellar bend propagation, which changed with calcium concentration. Reversal of the direction of bend propagation was accompanied by a reversal of direction of the rotational movement of the spermatozoa around their long axis, suggesting that the bending waves keep the sense of their three-dimensional form. The swimming speed of apyrene spermatozoa in natural seawater was about one-eighth of that of the eupyrene ones and remained almost constant in highly viscous medium. The swimming speed of conjugated eupyrene spermatozoa was the same as that of unpaired spermatozoa over a wide viscosity range (<3,000 cP). No advantage of swimming by two spermatozoa could be detected in Turritella spermatozoa.
海蜗牛（Turritella communis）产生两种类型的精子，分别称为无核精子和有核精子。有核精子通常成对出现，但未成对的精子也参与受精过程。使用带有高速快门的摄像机对这些精子的运动进行了分析。有核精子通常头部朝前游动，但也能够鞭毛朝前游动。发现它们游泳方向的反转是鞭毛弯曲传播方向变化的结果，而这种变化随钙浓度而改变。弯曲传播方向的反转伴随着精子围绕其长轴旋转运动方向的反转，这表明弯曲波保持了它们三维形态的感知。在天然海水中，无核精子的游动速度约为有核精子的八分之一，并且在高粘性介质中几乎保持恒定。在较宽的粘度范围内（<3000厘泊），结合的有核精子的游动速度与未成对精子的游动速度相同。在海蜗牛精子中未检测到两个精子一起游动的优势。
