Ultrastructure of ganglia in the brachiopod Coptothyris grayi and its phylogenetic significance. (21st October 2020)

• Record Type: Journal Article
• Authors: Kuzmina, Tatyana; Temereva, Elena
• Is Part Of: Journal of zoological systematics and evolutionary research. Volume 59:Number 2(2021)
• Page Start: 376
• Page End: 386
• Publication Date: 2020-10-21
• Subjects: brachiopods -- ganglion -- glial cells -- nervous system -- neuroepithelium; Animals -- Classification -- Periodicals; Zoology -- Periodicals; Evolution -- Periodicals; 578.012
• DOI: 10.1111/jzs.12427
• Languages: English
• ISSNs: 0947-5745

Abstract

Abstract: Since the study of the neuroarchitecture has phylogenetic value, it is important to describe the nervous system in poor investigated groups. We describe the ultrastructure of the supraenteric and subenteric ganglia in the rhynchonelliform brachiopod Coptothyris grayi . We found that the supraenteric ganglion is a neuroepithelium that consists of monociliated neurons among glial cells and a basal neuropil. The subenteric ganglion contains neurons of two morphologically distinct types and is represented by a stratified neuroepithelium with three layers. The apical layer is formed by the somata of glial cells. The middle layer contains the large perikarya of the neurons of the first type. The inner basal layer consists of a neuropil, basal projections of glial cells, and neurons of the second type. The brachiopod supraenteric ganglion exhibits the features of the simple neuroepithelium that is probably the plesiomorphic condition in the bilaterian ancestor. The brachiopod subenteric ganglion is a stratified neuroepithelium that has been described in some groups of protostomes and deuterostomes. The next step in the evolution of the invertebrate nervous system was an internalization. In many groups of protostomes, the subepidermal ganglia, which consist of perikarya surrounding a central neuropil, are formed by ingression of the neuroepithelium. In deuterostomes, the nerve tube with an inner neural canal is formed by invagination of the stratified neuroepithelium. Thus, the so‐called ganglia of brachiopods are neuroepithelia that have retained the plesiomorphic condition of the bilaterian nervous system and that cannot be regarded as true ganglia. Abstract : So‐called ganglia of brachiopods are represented by neuroepithelia. In evolution, true ganglia are formed by invagination or ingression of the neuroepithelium.