During meiosis, homologous chromosomes exchange genetic material. This exchange or meiotic recombination is mediated by a proteinaceous scaffold known as the Synaptonemal complex (SC). Any defects in its formation produce failures in meiotic recombination, chromosome segregation and meiosis completion. It has been proposed that DNA repair events that will be resolved by crossover between homologous chromosomes are predetermined by the SC. Hence, structural analysis of the organization of the DNA in the SC could shed light on the process of crossover interference. In this work, we employed an ultrastructural DNA staining technique on mouse testis and followed nuclei of pachytene cells. We observed structures organized similarly to the SCs stained with conventional techniques. These structures, presumably the DNA in the SCs, are delineating the edges of both lateral elements and no staining was observed between them. DNA in the LEs resembles two parallel tracks. However, a bubble-like staining pattern in certain regions of the SC was observed. Furthermore, this staining pattern is found in SCs formed between non-homologous chromosomes, in SCs formed between sister chromatids and in SCs without lateral elements, suggesting that this particular organization of the DNA is determined by the synapsis of the chromosomes despite their lack of homology or the presence of partially formed SCs.

在减数分裂期间，同源染色体交换遗传物质。这种交换或减数分裂重组是由称为突触复合物（SC）的蛋白质支架介导的。其形成中的任何缺陷都会导致减数分裂重组，染色体分离和减数分裂完成失败。已经提出由SC预先确定将通过同源染色体之间的交换来解决的DNA修复事件。因此，对SC中DNA的组织进行结构分析可以揭示交叉干扰的过程。在这项工作中，我们在小鼠睾丸上采用了超微结构DNA染色技术，然后跟踪了粗线细胞的细胞核。我们观察到的结构类似于用常规技术染色的SC。这些结构，大概是SC中的DNA，描绘了两个侧边元件的边缘，并且在它们之间未观察到染色。LE中的DNA类似于两条平行的轨道。但是，在SC的某些区域观察到了气泡状的染色图案。此外，在非同源染色体之间形成的SC，姐妹染色单体之间形成的SC以及无侧向元素的SC中都发现了这种染色模式，这表明DNA的这种特殊组织是由染色体的突触决定的，尽管它们缺乏同源性。或存在部分形成的SC。