罗氏沼虾精子发生的超微结构

应用透射电镜技术，研究了罗氏沼虾精子发生的全过程．观察表明：精原细胞较大，近卵圆形，核大而圆，染色质分散．初级精母细胞比精原细胞略小，染色质凝聚成块状，散布于核质中．次级精母细胞呈多边形，染色质致密，核膜双层，细胞质和核质问通过核孔进行物质交换．精细胞近圆形或多边形，染色质较密集地均匀分布，胞质较丰富，有线粒体、游离核糖体和内质网分布．精子分化早期，染色质向胞核的一侧移动，随着分化的进行，精细胞核逐渐拉长，变得弯曲．分化晚期，细胞质中出现许多膜片层结构，分泌一些碎细丝状物质，沿核的边缘向核凸起的一端推进，不断聚集、突起，最终形成具横纹精子的棘突．成熟的精子呈漏斗状，包括一个杯形的核和由其发出的一个横纹状棘突．

Ultrastructure of spermatogenesis in freshwater prawn,Macrobrachium rosenbergii (Crustacea: Decapoda)

Spermatogenesis of the freshwater prawn Macrobrachium rosenbergii was studied with transmission electron microscope (TEM). Spermatogonium was big and oval. The nucleus was round and the chromatin was dispersed. The primary spermatocyte was a little bit smaller in size than spermatogoium. The chromatin began to condense to be little or big pieces. Most of the secondary spermatocytes were polygonous, the chromatin was condensed to be big pieces. The nucleo-cytoplasmic exchange through nuclear pores in the double-layered nuclear membranes could be observed in the secondary spermatocyte. Spermatid was nearly round or polygonous, in which there were some mitochondria, ribosomes and endoplasmic reticula in the cytoplasm. The chromatin was densely distributed. In the early stage of spermiogenesis, the chromatin moved to the edge and then toward one side of the nucleus. During spermiogenesis, the nucleus became longer and then bended to be hemisphere. At the later stage of spermiogenesis, many stacks of lamellar membranes appeared in the cytoplasm. Some filamentous pieces moved out from the lamellar stacks, then gathered at one side, which made this side became convex and developed into a cross-striated spike. The mature sperm had a cup-shaped nucleus, with a cross-striated spike projecting from the cup.