Vogl A W
Department of Anatomy, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Int Rev Cytol. 1989;119:1-56. doi: 10.1016/s0074-7696(08)60648-8.
Actin filaments are concentrated in specific regions of spermatogenic cells and Sertoli cells. In spermatogenic cells they occur in intercellular bridges and in the subacrosomal space. In Sertoli cells they are abundant in ectoplasmic specializations and in regions adjacent to tubulobulbar processes of spermatogenic cells. At all of these sites, the filaments are morphologically related to the plasma membrane and+or intercellular membranes, and, as in many other cell types, are arranged in either bundles or networks. In at least two of the locations just indicated (ectoplasmic specializations and intercellular bridges), elements of the ER are closely related to the actin filaments. In tubulobulbar complexes, ER is present but is more distantly related to the filaments. Elements of the ER, when present, may serve a regulatory function. The filaments in ectoplasmic specializations and in regions adjacent to tubulobulbar processes of spermatogenic cells are suspected to be involved with the mechanism by which intercellular junctions are established, maintained, and degraded. In intercellular bridges, actin filaments may serve to reinforce and perhaps regulate the size of the cytoplasmic connections between differentiating germ cells. Filaments in the subacrosomal space may serve as a linking network between the acrosome and nucleus and may also be involved in the capping process. Because of the possibility that the actin filaments discussed before may be related to specific membrane domains involved with intercellular or interorganelle attachment, and that changes in these membrane domains are prerequisite to processes such as sperm release, turnover of the blood-testis barrier, formation of the acrosome, and coordination of spermatogenic cell differentiation, an understanding of exactly how these actin filaments are related to elements in the membrane and how this interaction is controlled is fundamental to our understanding, and perhaps our manipulating, of male fertility. I suspect that working out the molecular organization of these actin filament-containing sites and determining how their organization is controlled will be the major focus of research in this field over the next few years.
肌动蛋白丝集中在生精细胞和支持细胞的特定区域。在生精细胞中，它们出现在细胞间桥和顶体下间隙。在支持细胞中，它们在外质特化结构以及与生精细胞管球突相邻的区域大量存在。在所有这些部位，这些细丝在形态上与质膜和/或细胞内膜相关，并且与许多其他细胞类型一样，排列成束状或网络状。在至少上述两个部位（外质特化结构和细胞间桥），内质网成分与肌动蛋白丝密切相关。在管球复合体中，内质网存在但与细丝的关系较远。内质网成分一旦存在，可能发挥调节功能。外质特化结构以及与生精细胞管球突相邻区域的细丝被怀疑参与了细胞间连接建立、维持和降解的机制。在细胞间桥中，肌动蛋白丝可能起到加强作用，也许还能调节分化中的生殖细胞之间细胞质连接的大小。顶体下间隙中的细丝可能作为顶体与细胞核之间的连接网络，也可能参与盖帽过程。鉴于之前讨论的肌动蛋白丝可能与涉及细胞间或细胞器间附着的特定膜结构域有关，并且这些膜结构域的变化是精子释放、血睾屏障更新、顶体形成以及生精细胞分化协调等过程的先决条件，那么准确了解这些肌动蛋白丝如何与膜中的成分相关以及这种相互作用是如何被控制的，对于我们理解甚至操控男性生育能力至关重要。我怀疑，在未来几年里，弄清楚这些含有肌动蛋白丝部位的分子组织以及确定其组织是如何被控制的，将成为该领域研究的主要焦点。
