Secretory Radial Glia in the Ectoneural System of the Sea Star <i>Asterias rubens</i> (Echinodermata)

Viehweg, Jens; Naumann, W.; Olsson, Ragnar

doi:10.1111/j.1463-6395.1998.tb01151.x

Cited by 28 publications

(58 citation statements)

References 61 publications

(34 reference statements)

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“…In both subsystems, the framework of the neuroepithelium is composed of supporting cells, whose major feature is the presence of bundles of intermediate filaments, which run the height of the cells from the apical to the basal surfaces. Similar cells were found in the ectoneural subsystem of many other echinoderms (Ma¨rkel and Ro¨ser 1991;Byrne 1994;Chia and Koss 1994;VandenSpiegel et al 1995;Viehweg et al 1998), but often were not called glial cells by the authors. Therefore, it has long been stressed that the echinoderm nervous tissue has no glia Cobb 1990Cobb , 1995.…”

Section: Neuroepitheliummentioning

confidence: 87%

“…However, some recent papers have challenged this view (Byrne 1994;Viehweg et al 1998;Heinzeller et al 2004). …”

Section: Introductionmentioning

confidence: 91%

“…In both holothuroidean species studied, as in all the other echinoderms, irrespective of whether they possess open or closed ambulacra, the ectoneural subsystem exhibits the organization of a neuroepithelium (Beklemishev 1964;Kawaguti 1965;Ma¨rkel and Ro¨ser 1991;Chia and Koss 1994;Viehweg et al 1998;Heinzeller and Welsch 2001). In holothuroidean, the hyponeural band is similar to the ectoneural tissue both in histological structure and cell composition.…”

Section: Neuroepitheliummentioning

confidence: 98%

“…It remains unclear whether the neurons are randomly distributed or, together with the glial supporting cells, form a specific pattern, as is the case in asteroid arms (Viehweg et al 1998). In the neuroepithelium of holothuroidean species, we distinguish the following nerve cell types:…”

Section: Nerve Cellsmentioning

confidence: 98%

“…Therefore, it has long been stressed that the echinoderm nervous tissue has no glia Cobb 1990Cobb , 1995. However, Viehweg et al (1998) showed that the supporting cells of the ectoneural cord of the asteroid Asterias rubens were labeled specifically with a polyclonal antiserum directed against Reissner's substance, which is commonly produced and secreted by the radial glia in chordates. In ophiuroid species, these cells seem to exhibit positive CRF-and S-100-like immunoreactivity (Heinzeller et al 2004).…”

Section: Neuroepitheliummentioning

confidence: 98%

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Ultrastructure of the circumoral nerve ring and the radial nerve cords in holothurians (Echinodermata)

et al. 2006

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The circumoral nerve ring and the radial nerve cords (RNCs) of Eupentacta fraudatrix and Pseudocnus lubricus (Holothuroidea) were examined as an example of holothurian nervous tissue. The RNC is composed of outer ectoneural and inner hyponeural layers, which are interconnected with one another via short neural bridges. The circumoral nerve ring is purely ectoneural. Both ectoneural and hyponeural components are epithelial tubes with a thick neuroepithelium at one side. A thin ciliated non-neuronal epithelium complements the neuroepithelium to form a tube, thereby enclosing the epineural and hyponeural canals. The whole of the ectoneural and hyponeural subsystems is separated from the surrounding tissue by a continuous basal lamina. The nerve ring and the ectoneural and hyponeural parts of the radial nerves are all neuroepithelia composed of supporting cells and neurons. Supporting cells are interpreted as being glial cells. Based on ultrastructural characters, three types of neurons can be distinguished:(1) putative primary sensory neurons, whose cilium protrudes into the epineural or hyponeural canal; (2) non-ciliated neurons with swollen rough endoplasmic reticulum cisternae; (3) monociliated neurons that are embedded in the trunk of nerve fibers. Different types of synapses occur in the neuropile area. They meet all morphological criteria of classical chemical synapses. Vacuolated cells occur in the neuroepithelium of E. fraudatrix, but are absent in P. lubricus; their function is unknown. The cells of the non-neuronal epithelia that overlie the ectoneural and hyponeural canals are hypothesized to belong to the same cell type as the supporting cells of the neuroepithelium.

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Section: Neuroepitheliummentioning

confidence: 87%

“…However, some recent papers have challenged this view (Byrne 1994;Viehweg et al 1998;Heinzeller et al 2004). …”

Section: Introductionmentioning

confidence: 91%

Section: Neuroepitheliummentioning

confidence: 98%

Section: Nerve Cellsmentioning

confidence: 98%

Section: Neuroepitheliummentioning

confidence: 98%

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Ultrastructure of the circumoral nerve ring and the radial nerve cords in holothurians (Echinodermata)

et al. 2006

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Radial Glia in Echinoderms

Mashanov

Zueva

2018

Developmental Neurobiology

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Radial glial cells are crucial invertebrate neural development and regeneration. It has been recently proposed that this neurogenic cell type might be older than the chordate lineage itself and might have been present in the last common deuterostome ancestor. Here, we summarize the results of recent studies on radial glia in echinoderms, a highly regenerative phylum of marine invertebrates with shared ancestry to chordates. We discuss the involvement of these cells in both homeostatic neurogenesis and post-traumatic neural regeneration, compare the features of radial glia in echinoderms and chordates to each other, and review the molecular mechanisms that control differentiation and plasticity of the echinoderm radial glia. Overall, studies on echinoderm radial glia provide a unique opportunity to understand the fundamental biology of this cell type from evolutionary and comparative perspectives.

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Organization of glial cells in the adult sea cucumber central nervous system

Mashanov

Zueva

García‐Arrarás

2010

Glia

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The nervous system of echinoderms has long been considered too unique to be directly comparable to the nervous system of other Deuterostomia. Using two novel monoclonal antibodies in combination with epifluorescence, confocal, and electron microscopy, we demonstrate here that the central nervous system of the sea cucumber Holothuria glaberrima possesses a major non-neuronal cell type, which shares striking similarities with the radial glia of chordates. The basic features in common include (a) an elongated shape, (b) long radial processes, (c) short lateral protrusions branching off the main processes and penetrating into the surrounding neuropile, (d) prominent orderly oriented bundles of intermediate filaments, and (e) ability to produce Reissner's substance. Radial glia account for the majority of glia cells in echinoderms and constitutes more than half of the total cell population in the radial nerve cord and about 45% in the circumoral nerve ring. The difference in glia cell number between those regions is significant, suggesting structural specialization within the seemingly simple echinoderm nervous system. Both cell death and proliferation are seen under normal physiological conditions. Although both glia and neurons undergo apoptosis, most of the mitotic cells are identified as radial glia, indicating a key role of this cell type in cell turnover in the nervous system. A hypothesis is proposed that the radial glia could be an ancestral feature of the deuterostome nervous system, and the origin of this cell type might have predated the diversification of the Chordata and Ambulacraria lineages.

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Secretory Radial Glia in the Ectoneural System of the Sea Star Asterias rubens (Echinodermata)

Cited by 28 publications

References 61 publications

Ultrastructure of the circumoral nerve ring and the radial nerve cords in holothurians (Echinodermata)

Ultrastructure of the circumoral nerve ring and the radial nerve cords in holothurians (Echinodermata)

Radial Glia in Echinoderms

Organization of glial cells in the adult sea cucumber central nervous system

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