The ventral nerve cord in Cephalocarida (Crustacea): New insights into the ground pattern of Tetraconata
The ventral nerve cord in Cephalocarida (Crustacea): New insights into the ground pattern of Tetraconata
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DOI：
10.1002/jmor.20213
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发表时间：
2014-03
影响因子：
1.5
通讯作者：
Martin E. J. Stegner;Georg Brenneis;S. Richter
中科院分区：
文献类型：
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作者：
Martin E. J. Stegner;Georg Brenneis;S. Richter
鲸类是甲壳纲动物，具有许多解剖学特征，被解释为与甲壳纲动物或Tetraconata相似。虽然腹神经索（VNC）已在许多其他节肢动物中进行了研究，以解决系统发育和进化的问题，存在的几个研究的cephalocarid VNC可以追溯到20年前，和有关的数据，特别是神经活性物质是太稀疏的比较。我们重新研究了成年Hutchinsoniella macracantha的VNC，将免疫标记（微管蛋白，5-羟色胺，RFamide，组胺）和核染色与共聚焦激光显微镜结合起来，并辅以基于连续半薄切片的3D重建。鲸类的食管下神经节包括三个节段的神经节（Md，Mx 1，Mx2），而一个单独的神经节出现在所有胸段和腹段1-8。腹部第9和第10节以及尾椎没有神经节。上颌神经节和胸神经节在其肢体神经支配模式中密切对应，其模式主要为四个节段连合，并且在每个身体侧面显示多达六个单独识别的5-羟色胺样免疫反应神经元，这超过了大多数其他四碳酸酯中发现的数量。腹神经节中每侧仅存在两个连合和两个5-羟色胺样免疫反应神经元。口胃神经系统在H. macracantha对应于其他甲壳类动物中的macracantha，并且除了其他结构之外，还包括一对侧神经突束。这些神经支配肠道以及各种躯干肌肉，并且独特地与不成对的正中神经突束相连。我们建议，大多数功能的cephalocarid腹神经索（VNC）是plesiomorphic相对于tetraconate地面模式。此外，我们认为，这种基础模式包括更多的5-羟色胺样神经元比迄今为止假设，并认为，一个姐妹组之间的关系Cephalocarida和Remipedia，最近的分子分析支持，发现没有神经解剖学的支持。J. Morphol. 275：269-294，2014.© 2013 Wiley Periodicals，Inc.
Cephalocarida are Crustacea with many anatomical features that have been interpreted as plesiomorphic with respect to crustaceans or Tetraconata. While the ventral nerve cord (VNC) has been investigated in many other arthropods to address phylogenetic and evolutionary questions, the few studies that exist on the cephalocarid VNC date back 20 years, and data pertaining to neuroactive substances in particular are too sparse for comparison. We reinvestigated the VNC of adult Hutchinsoniella macracantha in detail, combining immunolabeling (tubulin, serotonin, RFamide, histamine) and nuclear stains with confocal laser microscopy, complemented by 3D‐reconstructions based on serial semithin sections. The subesophageal ganglion in Cephalocarida comprises three segmental neuromeres (Md, Mx1, Mx2), while a separate ganglion occurs in all thoracic segments and abdominal segments 1–8. Abdominal segments 9 and 10 and the telson are free of ganglia. The maxillar neuromere and the thoracic ganglia correspond closely in their limb innervation pattern, their pattern of mostly four segmental commissures and in displaying up to six individually identified serotonin‐like immunoreactive neurons per body side, which exceeds the number found in most other tetraconates. Only two commissures and two serotonin‐like immunoreactive neurons per side are present in abdominal ganglia. The stomatogastric nervous system in H. macracantha corresponds to that in other crustaceans and includes, among other structures, a pair of lateral neurite bundles. These innervate the gut as well as various trunk muscles and are, uniquely, linked to the unpaired median neurite bundle. We propose that most features of the cephalocarid ventral nerve cord (VNC) are plesiomorphic with respect to the tetraconate ground pattern. Further, we suggest that this ground pattern includes more serotonin‐like neurons than hitherto assumed, and argue that a sister‐group relationship between Cephalocarida and Remipedia, as favored by recent molecular analyses, finds no neuroanatomical support. J. Morphol. 275:269–294, 2014. © 2013 Wiley Periodicals, Inc.