Syncytial cytoplasmic anastomoses between the neu-rites of caudal mesenteric ganglion cells in adult cats

Abstract

Since the majority of the published data on syncytial cytoplasmic anastomoses relate to the autonomic nervous system in the early postnatal period of development, when many nerve fibers are still poorly covered by glia or have no glial sheaths at all, it was suggested that such anastomoses were not present in adults due to the significant development of glia separating individual neurites from each other. To check this assumption, we have performed an electron microscopic study of the adult cat dorsal caudal mesenteric ganglion. The cell neurites were found to be frequently covered by glial sheaths. However, almost in every sample, the syncytial pores were detected between the contacting neurites lacking glial covering layers. Sometimes serial syncytially connected neurites were seen. Axo-dendritic synapses with presynaptic perforations outside the synaptic specializations were described in the autonomic nervous system for the first time. These observations therefore provide evidence of syncytial cytoplasm connections in normal adult animals, however this does not reject the neuronal doctrine.

Keywords

interneuronal anastomoses / axo-dendritic synapses / caudal mesenteric ganglion / autonomic nervous system

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