The ground pattern underlying the nervous system of the last common ancestor in annelids was long thought to be settled, consisting of a dorsal brain, circumoesophageal connectives and a subepithelial, ladder-like ventral nerve cord with segmental ganglia connected by paired connectives. With the advent of immunocytochemical stainings and confocal laser scanning microscopy, it becomes evident that its architecture is extremely diverse, which makes the reconstruction of a ground pattern in annelida challenging. Whereas the nervous systems of many different families has already been described, only very few studies looked at the diversity of nervous systems within such clades to give a closer estimate on how plastic the annelid nervous system really is. So far, little is known on syllid nervous system architecture, one of the largest and most diverse groups of marine annelids. The position of the brain, the circumoesophageal connectives, the stomatogastric nervous system, the longitudinal nerves that traverse each segment and the innervation of appendages are relatively uniform within the clade. Both the number of connectives within the ventral nerve cord and the number of segmental nerves, which in earlier studies were used to infer phylogenetic relationships and to reconstruct an annelid ground pattern, are highly diverse and differ between genera or even within a given genus. Differences in the distribution of somata of the brain, the nuchal innervation and its associated cell bodies were found between Syllinae and Exogoninae and may be subfamily-specific. The nervous system morphology of syllids very likely depends on the taxon-specific ecological requirements. Thus, it is not surprising that in a clade, which occupies such diverse niches as the Annelida, we find similar patterns in phylogenetically widely separated species in similar niches and a high degree of modularity within a family. Only standardized protocols and staining methods can lead to comparable results, but so far different approaches have been taken to describe annelid nervous systems, making homologization of certain structures difficult. This study provides the first thorough description of the nervous system in the family Syllidae, allowing more detailed comparisons between annelid families in the future.

中文翻译：

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Syllidae (Annelida, Errantia) 神经系统结构的家族内可塑性。

环节动物最后一个共同祖先的神经系统的基础模式长期以来被认为是固定的，由背脑、食管环结缔和上皮下阶梯状腹神经索组成，节段神经节由成对结缔组织连接。随着免疫细胞化学染色和共聚焦激光扫描显微镜的出现，很明显它的结构极其多样化，这使得在环节动物中重建地面图案具有挑战性。尽管已经描述了许多不同家族的神经系统，但只有很少的研究着眼于这些进化枝中神经系统的多样性，以更接近地估计环节动物神经系统的可塑性。到目前为止，关于舌状神经系统结构知之甚少，最大和最多样化的海洋环节动物群之一。大脑的位置、食道周围结缔组织、口胃神经系统、横穿各节段的纵神经和附属物的神经支配在进化枝内相对一致。腹神经索内的连接物数量和节段神经的数量，在早期的研究中被用来推断系统发育关系和重建环节动物的地面模式，它们是高度多样化的，并且在属之间甚至在给定属内都不同。在 Syllinae 和 Exogoninae 之间发现了大脑体细胞分布、颈部神经支配及其相关细胞体的差异，并且可能是亚科特异性的。sylids 的神经系统形态很可能取决于分类单元特定的生态要求。因此，毫不奇怪，在一个像 Annelida 这样占据如此多样化生态位的进化枝中，我们在相似生态位的系统发育上广泛分离的物种中发现了相似的模式，并且在一个家庭内具有高度的模块化。只有标准化的协议和染色方法才能产生可​​比较的结果，但到目前为止，已经采用不同的方法来描述环节动物神经系统，使得某些结构的同源化变得困难。这项研究首次全面描述了 Syllidae 家族的神经系统，从而可以在未来对环节动物家族进行更详细的比较。我们在相似生态位中的系统发育上广泛分离的物种中发现了相似的模式，并且在一个家庭内具有高度的模块化。只有标准化的协议和染色方法才能产生可​​比较的结果，但到目前为止，已经采用不同的方法来描述环节动物神经系统，使得某些结构的同源化变得困难。这项研究首次全面描述了 Syllidae 家族的神经系统，从而可以在未来对环节动物家族进行更详细的比较。我们在相似生态位中的系统发育上广泛分离的物种中发现了相似的模式，并且在一个家庭内具有高度的模块化。只有标准化的协议和染色方法才能产生可​​比较的结果，但到目前为止，已经采用不同的方法来描述环节动物神经系统，使得某些结构的同源化变得困难。这项研究首次全面描述了 Syllidae 家族的神经系统，从而可以在未来对环节动物家族进行更详细的比较。使某些结构的同源化变得困难。这项研究首次全面描述了 Syllidae 家族的神经系统，从而可以在未来对环节动物家族进行更详细的比较。使某些结构的同源化变得困难。这项研究首次全面描述了 Syllidae 家族的神经系统，从而可以在未来对环节动物家族进行更详细的比较。