刺巨藤壶精子的发生及其超微结构

采用扫描和透射电镜技术, 观察刺巨藤壶(Megabalanus volcano)精子发生和精子的超微结构特征。结果显示, 刺巨藤壶精子发生经历精原细胞、初级精母细胞、次级精母细胞、精细胞和精子等5个阶段。在精子形成期间, 圆形或椭圆形的细胞核在微管的作用下沿轴丝延长并在胞质内弯曲, 核和轴丝随着精细胞的纵向伸长而延长, 细胞核最终成为线状; 斑块状的染色质逐渐解体, 呈细小颗粒状和粗颗粒状, 最后浓缩成高密度的均质物; 高尔基体分泌的囊泡不断融合, 形成大小不一的附属小滴前体, 最后融合并延伸成一个纺锤形的附属小滴; 许多小的线粒体不断融合成一个细长的线粒体, 移至核的后端。精子为前部带有附属小滴的长线状, 全长约58.39μm, 可分为顶体、颈部、中段和尾部四部分。长锥形的顶体位于精子最前端, 其后为基体; 颈部由基体产生的“9+2”型轴丝和与之并行的线状核组成; 顶体和颈部两者长共约6.65μm。中部长约42.95μm, 纺锤形的附属小滴(长约9.33μm, 最宽处约2.13μm)紧靠核和轴丝, 其后为颗粒状糖原及一个细长的线粒体; 尾部长约8.79μm, 只有轴丝贯穿。

Ultrastructure of spermatogenesis and spermatozoon of Megabalanus volcano

The ultrastructural characteristics of spermatogenesis and spermatozoon of the barnacle Megabalanus volcano were observed by scanning and transmission electron microscopy. The results showed that its spermatogenesis included five developmental stages, i.e., spermatogonium, primary spermatocyte, secondary spermatocyte, spermatid, and mature spermatozoon. During spermatogenesis, a circular or oval nucleus extended along with an axial filament and bent in cytoplasm under the action of microtubules. The nucleus further elongated with longitudinal extension of a spermatid, and finally became filiform. Massive chromatin of nucleus underwent disintegration, fine granules, coarse granules, and eventually condensed into a high electron density homogenizer. The vesicles secreted by the Golgi complex coalesced to different sizes of precursors of accessory droplet, and finally fused into an accessory droplet of high electron density. Many small mitochondria fused to a slender one that was eventually positioned behind the nucleus. The spermatozoon (about 58.39 μm in length), which was divided into acrosome, neck, middle piece, and tail, was long filiform with an accessory droplet. The conical acrosome was located at the spermatozoon anterior, followed by a basal body. The neck was composed of a "9+2" type axial filament, and the filiform nucleus was parallel to the axial filament. The length of acrosome and neck was about 6.65 μm. The middle piece was about 42.95 μm in length. The spindle-shaped accessory droplet (about 9.33 μm long and 2.13 μm wide) was adjacent to the nucleus and axial filament, followed by a mass of glycogenosomes and a slender mitochondrion. The tail (about 8.79 μm in length) only had a typical "9+2" axial filament.