Hulsebosch C E, Bittner G D
J Comp Neurol. 1981 May 1;198(1):65-75. doi: 10.1002/cne.901980107.
Neurons of the ventral nerve cord (VNC) in the polychaete species Clymenella torquata and Nereis virens were ultrastructurally distinguished from glial cells by the smaller diameter and elongated shape of glial nuclei in adult organisms. In contrast to neurons, beta-glycogen-like particles and densely packed microfilaments were found in glial cytoplasm. Using these and other criteria, glial cells were distinguished from nerve cells in histologic preparations. All neuronal nuclei were counted in specified regions of the CNS of both polychaetes. In both species, the number of neuronal nuclei in various CNS regions remained constant in animals of very different body size. Since Clymenella has a set number of ganglia in the VNC and a set number of body segments, the total number of CNS neurons remains constant in adult members of this species. Since adult Nereis adds VNC ganglia in newly forming body segments, the total number of CNS neurons continuously increases, but the total number of CNS neurons in a ganglion does not change after it is formed.
在多毛纲动物托氏索沙蚕和绿沙蚕中，成年生物体腹神经索（VNC）中的神经元在超微结构上与神经胶质细胞不同，神经胶质细胞核直径较小且呈细长形。与神经元不同，在神经胶质细胞质中发现了β-糖原样颗粒和密集排列的微丝。利用这些及其他标准，在组织学标本中区分出了神经胶质细胞和神经细胞。对这两种多毛纲动物中枢神经系统（CNS）的特定区域内的所有神经元细胞核进行了计数。在这两个物种中，不同体型的动物中枢神经系统各区域的神经元细胞核数量保持恒定。由于托氏索沙蚕腹神经索中的神经节数量固定，且身体节段数量固定，该物种成年个体的中枢神经系统神经元总数保持恒定。由于成年绿沙蚕在新形成的身体节段中增加腹神经索神经节，中枢神经系统神经元总数持续增加，但神经节形成后其中枢神经系统神经元总数不变。
