六种鱼的精母细胞联会复合体的电镜观察

我们以界面铺张——硝酸银染色技术,对鲈形目三种鱼(尼罗罗非鱼、莫桑比克罗非鱼、刺鳅)和鲤形目(鱼句)亚科三种鱼(花(鱼骨)、黑鳍鳈、麦穗鱼)的精母细胞联会复合体进行了电镜观察研究。系统考察了鱼类常染色体SC的亚显微结构、形成过程和配对行为,比较分析了刺鳅的性染色体SC的异配形态和行为,并绘制了鲈形目三种鱼的SC组型模式图。

Electron Microscopic Observation of Synaptonemal Complexes in Spermatocytes of Six Species of Fishes

The synaptonemal complexes (SCs) in spermatocytes of six species of fishes were detected with a combination of surface spreading and silver staining technique and observed under both light and electron microscopes. These fishes are Tilapia nilotica, T. mossambica and Masiacembelus sinensis of Perciformes. Sarcocheilichthys nigripinnis, Pseudorasbora parva and Hemibarbus maculatus of Gobioninae in Cypriniformes.The formation of SCs started in Zygotene and completed at Pachytene. During the pachytene, each SC was morphologically intact, preferentially stained and attached to the nuclear envelope by a dense terminal plaque. Interlock in SCs frequently occurred in Zygotene. In several cases breakage and disentangling of interlocked lateral elements were observed. SCs disappeared in diplotene.The pairing of the SCs started at telomeres and stretched towards kinetochore.The sex determination of Mastacembeltts sinensis was xx/xy. The X and Y chromosomal SCs' axes had a distinctive morphology at pachytene and were clearly distinguishable from au-tosomal SCs. The X and Y chromosomes begain to pair at early pachytene. The X and Y chro mosome axes paired to form a length of SC that is somewhat longer than the unpaired portion at the mid-pachytene. There was a dense substance at unpaired portion.Quantitatine evaluation demonstrated that relative length and arm ratio were distinctive characteristics for each autosomal SC. The consistency of relative length and arm ratio indicates the stability of the techniques. The idiograms of SC karyotypes of three species niloticus, T. mossambicus and Mastacembelus sinensis) have been constructed.