Michalik P, Dallai R, Giusti F, Alberti G
Zoologisches Institut und Museum, Ernst-Moritz-Arndt-Universität, J.-S.-Bach-Strasse 11/12, D-17489 Greifswald, Germany.
Tissue Cell. 2004 Dec;36(6):447-60. doi: 10.1016/j.tice.2004.08.001.
The present study reports on the ultrastructure features of spermatozoa and spermatogenesis of several species of Dysderidae (Dysdera crocata, Dysdera erythrina, Dysdera ninnii, Harpactea arguta, Harpactea piligera, Dasumia taeniifera). Dysderid spiders are known to possess a peculiar sperm transfer form known as synspermia, characterized by fused spermatozoa surrounded by a secreted sheath. Until now the exact mode of formation of the synspermia is unknown. The present study demonstrates that the spermatids are connected via narrow cell bridges during the entire spermiogenesis as is usual, although in Dysderidae they do not separate at end of the spermiogenesis. Instead, they fuse completely within the testes shortly after the spermatid has coiled to get a spherical shape. The number of fusing sperm cells is different in the different observed species. The species of the genus Harpactea thus have synspermia consisting of two fused spermatozoa; whereas in the species of the genus Dysdera four sperm cells are fused and in D. taeniifera at least three spermatozoa are fused. In contrast with other known families with this peculiar form transfer of sperm, the synspermia in Dysderidae are mainly characterized by a conspicuous vesicular area which extends through the entire synspermium surrounding the cell organelles. Thus, all main cell components (e.g., nucleus, acrosomal vacuole, and axoneme) are covered by the vesicular membrane. The vesicular area seems to be functional and probably it is important during sperm activation in female genital system. Simultaneously to the extension of the vesicular area, the synspermium accumulates large amounts of glycogen. The glycogen is mainly located around the centriolar adjunct and along the axoneme accompanying the postcentriolar elongation of the nucleus. A further peculiar feature is the extremely elongated acrosomal vacuole, which seems to be synapomorphic trait for sperm cells of dysderids. Interestingly, spermatogenesis, including the fusion, exclusively occurs within the testes (in contrast to the formation of coenospermia). In the vas deferens only synspermia were found. The secreted sheath surrounding the spermatozoa is finally synthesized in the parts of the vasa deferentia, which are close to the genital opening where numerous vacuoles and microvilli are seen in the epithelial cells.
本研究报告了几种隙蛛科蜘蛛（横带隙蛛、红隙蛛、宁氏隙蛛、锐毛刺猛蛛、毛毛刺猛蛛、带纹达苏蛛）精子及精子发生的超微结构特征。已知隙蛛科蜘蛛具有一种特殊的精子传递形式，称为联精现象，其特征是融合的精子被一层分泌的鞘所包围。到目前为止，联精的具体形成方式尚不清楚。本研究表明，在整个精子形成过程中，精子细胞通过狭窄的细胞桥相连，这是常见的情况，不过在隙蛛科中，精子细胞在精子形成结束时并不分离。相反，在精子细胞盘绕成球形后不久，它们就在睾丸内完全融合。在不同观察物种中，融合的精子细胞数量不同。因此，刺猛蛛属的物种具有由两个融合精子组成的联精；而在隙蛛属的物种中，四个精子细胞融合，在带纹达苏蛛中至少有三个精子融合。与其他具有这种特殊精子传递形式的已知科不同，隙蛛科的联精主要特征是有一个明显的泡状区域，该区域贯穿整个围绕细胞器的联精。因此，所有主要的细胞成分（如细胞核、顶体泡和轴丝）都被泡状膜覆盖。泡状区域似乎具有功能，并且可能在精子在雌性生殖系统中的激活过程中很重要。在泡状区域扩展的同时，联精积累了大量糖原。糖原主要位于中心粒附属物周围以及伴随细胞核中心粒后伸长的轴丝沿线。另一个独特特征是顶体泡极其细长，这似乎是隙蛛科精子细胞的一个共衍征性状。有趣的是，包括融合在内的精子发生仅在睾丸内发生（与共精的形成不同）。在输精管中只发现了联精。包围精子的分泌鞘最终在输精管靠近生殖孔的部分合成，在那里上皮细胞中可见大量液泡和微绒毛。
