Department of Evolutionary Biology, University of Siena, Siena, Italy.
Arthropod Struct Dev. 2011 Jan;40(1):77-92. doi: 10.1016/j.asd.2010.08.001. Epub 2010 Oct 28.
Sperm ultrastructure and spermiogenesis of the dipluran Japygidae (Japyx solifugus, Metajapyx braueri and Occasjapyx japonicus) and Campodeidae (Campodea sp.) were studied with the aim of looking for potential characters for the reconstruction of the phylogenetic relationships of basal hexapods. Both Japygidae and Campodeidae share a common sperm axonemal model 9+9+2, provided with nine accessory microtubules. These microtubules, however, after their formation lose the usual position around the 9+2 and migrate between the two mitochondria. In Japygidae, four of these microtubules are very short and were observed beneath the nucleus after negative staining and serial sections. Accessory microtubules have 13 protofilaments in their tubular wall. Diplura have a sperm morphology which is very different from that of the remaining Entognatha (Protura+Collembola). On the basis of the present results, the presence of accessory microtubules suggests that Diplura are the sister-group of the Insecta s.s.. Moreover, Japygidae and Campodeidae differ with regards to the relative position of the sperm components, the former having the axoneme starting from beneath the nucleus (above which sits the short acrosome), while the latter having a long apical acrosome and a nucleus running parallel with the proximal part of the axoneme. The present study also allowed to redescribe the male genital system of Japyx.
双尾目（Japyx solifugus、Metajapyx braueri 和 Occasjapyx japonicus）和栉角蝇科（Campodea sp.）精子超微结构和精子发生的研究旨在寻找可能的特征，以重建基础六足动物的系统发育关系。双尾目和栉角蝇科都具有共同的精子轴丝模型 9+9+2，配备了 9 个附加微管。然而，这些微管在形成后失去了围绕 9+2 的通常位置，并在两个线粒体之间迁移。在双尾目，其中四个微管非常短，在负染色和连续切片后观察到位于核下方。附加微管在其管状壁上有 13 个原纤维。双尾目具有与其余内口纲（原尾目+弹尾目）非常不同的精子形态。基于目前的结果，附加微管的存在表明双尾目是昆虫纲的姊妹群。此外，双尾目和栉角蝇科在精子成分的相对位置上存在差异，前者的轴丝从核下方开始（核上方是短的顶体），而后者具有长的顶体和与轴丝近端平行的核。本研究还允许重新描述 Japyx 的雄性生殖系统。
