The synaptonemal complex (SC), a highly conserved structure built between homologous meiotic chromosomes, is required for crossover formation and ensuring proper chromosome segregation. In many organisms, SC components can also form alternative structures, including repeating SC structures that are known as polycomplexes (PCs), and extensively modified SC structures that are maintained late in meiosis. PCs display differences in their ability to localize with lateral element proteins, recombination machinery, and DNA. They can be created by defects in post-translational modification, suggesting that these modifications have roles in preventing alternate SC structures. These SC-like structures provide insight into the rules for building and maintaining the SC by offering an ‘in vivo laboratory’ for models of SC assembly, structure, and disassembly. Here, we discuss what these structures can tell us about the rules for building the SC and the roles of the SC in meiotic processes.

突触复合物（SC）是在同源减数分裂染色体之间建立的高度保守的结构，对于交叉形成和确保正确的染色体分离是必需的。在许多生物中，SC成分还可以形成其他结构，包括称为多复合体（PC）的重复SC结构以及在减数分裂后期维持的广泛修饰的SC结构。PCs在横向元素蛋白，重组机制和DNA定位方面表现出差异。它们可能是由翻译后修饰中的缺陷造成的，表明这些修饰在防止其他SC结构中具有作用。这些类似SC的结构通过提供“体内”功能，可以深入了解构建和维护SC的规则。用于SC组装，结构和拆卸的模型的“实验室”。在这里，我们讨论这些结构可以告诉我们有关构建SC的规则以及SC在减数分裂过程中的作用的信息。