蟹类精子超微结构的比较研究

STUDIES ON THE COMPARATIVE ULTRASTRUCTURE OF CRAB SPERMATOZOA (Crustacea,Decapoda,Reptantia,Brachyura)

应用光镜和电镜， 比较研究三疣梭子蟹（ Ｐｏｒｔｕｎｕｓｔｒｉｔｕｂｅｒｃｕｌａｔｕｓ） 、中华绒螯蟹（ Ｅｒｉｏｃｈｅｉｒｓｉｎｅｎｓｉｓ）和长江华溪蟹（Ｓｉｎｏｐｏｔａｍｏｎ ｙａｎｇｔｓｅｋｉｅｎｓｅ） 的成熟精子。揭示３ 种蟹精子都是不能游动的无鞭毛精子， 呈球形，前后略扁。精子前端出现一光滑的小圆面， 圆面四周有内陷的沟环。沟环之后， 精子表面凹凸不平， 并伸出多数辐射臂。３ 种蟹精子均为高度特化的细胞， 外被质膜， 内含细胞核、顶体及退化的细胞质。核前面内凹， 呈杯状， 因称核杯。核杯外被基本上连续完整的核膜； 染色质不浓缩， 呈细网状。核杯外侧的突出物形成辐射臂。顶体宛如落入核杯内的一个小球， 结构复杂， 外被顶体膜， 分为顶体囊、头帽和顶体管３ 部分。退化的细胞质分布于核杯和顶体之间， 内有膜复合体。另外， ３ 种蟹精子在超微结构上也存在一定的差异。

Comparative sperm morphology of three species of crab, Portunus trituberculatus,Eriocheir sinensis and Sinopotamon yangtsekiense have been investigated with light and electron microscopes.These sperms are aflagellate and typical brachyurans.SEM observation shows:1)each sperm has a spherical body,2)the anterion part appears smooth,and the other part is uneven,from which 10-20 radial arms radiate,3)there is a ditch ring between the two parts. TEM reveals that each sperm is composed of acrosome,cytoplasmic region,nuclear cup and radial arms.The globular acrosome is a very complicated structure and shows PAS positive.Its centre is a cylindrical acrosomal tubule and its front is an apical cap.The acrosome is limited by an single continuous membrane and surrounded by nuclear cup,which shows Feulgen positive.The nuclear cup contains uncondensed chromatin and is bounded by a complete nuclear envelope.The radial arms are extensions of the nuclear cup.They are stational,then the sperm are immotile.There are no microtubular elements in the arm.The cytoplasmic region is posterior to the acrosome and consists of lamellar complex.Several differences exist the crab spermatozoa in three species.