Crustacean visual system: an investigation on glial cells and their relation to extracellular matrix

Silva, Simone Florim da; Taffarel, M; Allodi, Silvana

doi:10.1016/s0248-4900(01)01120-0

Cited by 19 publications

(15 citation statements)

References 33 publications

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“…] typically within the sheath, resembles superficially, at least, cells of a similar character in our copepod material. These two types of CNS glial cells, electron-dense and electron-lucent, have been confirmed in studies on crab brain in Silvana Allodi's laboratory (see, e.g., da Silva et al, 2001). However, a salient type of decapod glial cell appeared to be missing in our copepod material: the Schwann cell produces multilayered ensheathments of axons interlaminated with often fibrous extracellular matrix in Reptantia (Geren and Schmidt, 1954;Radojcic and Pentreath, 1979;Villegas and Sánchez, 1991) and semicompact myelin supporting saltatory conduction in Natantia (Huang et al, 1963;Kusano, 1966;Xu and Terakawa, 1999).…”

Section: From What Sources Might Intracellular Myelin Develop?mentioning

confidence: 65%

Novel organization and development of copepod myelin. ii. nonglial origin

Wilson

Hartline

2011

J of Comparative Neurology

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Nerve-impulse conduction is greatly speeded by myelin sheaths in vertebrates, oligochaete annelids, penaeid and caridean shrimp, and calanoid copepods. In the first three invertebrate cases, myelin arises from glial cells, as it does in vertebrates. The contribution of the glial cells to the layered structure of the myelin is clear: their nuclei are either embedded in the layers or reside in contiguous cytoplasmic compartments, and their cell membranes are seen to be continuous with those of the myelin layers. However, with calanoids, the association with glial cells presumed necessary to generate the myelin has never been satisfactorily identified. We have conducted a systematic examination of thin sections through different parts of the copepod nervous system to identify the structural organization of copepod myelin and the likely mechanism for its formation. We find that myelination appears to commence by laying down and compacting a cisternal tongue against the inside of the axolemma. This is followed by the successive layering and compaction of additional tongues to create a stack of tongues. The margins of the tongues then expand to encircle the interior of a neurite, meeting and fusing to form complete concentric myelin. No sign of glial involvement could be detected at any stage. Unlike glially derived myelin, the extracellular tracer lanthanum did not penetrate between the myelin layers in copepods, further evidence against a glial source. We believe this to be the first demonstration of a nonglial origin for myelin in any species.

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Section: From What Sources Might Intracellular Myelin Develop?mentioning

confidence: 65%

Novel organization and development of copepod myelin. ii. nonglial origin

Wilson

Hartline

2011

J of Comparative Neurology

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“…Invertebrate glial cells display variable morphologies depending on species and location and have been classifi ed according to certain general morphological or functional criteria [Hamori and Horridge, 1966;Radojcic and Pentreath, 1979;da Silva et al, 2001], however their function during axon degeneration has not been completely established. Some authors state that there is not a strong correlation between nerve fi bers and glial cell response during degeneration [Bittner et al, 1974;Clark, 1976;Blundon et al, 1990], whereas others report a phagocytic function for these cells [Radojcic and Pentreath, 1979;Kretzschmar and Pfl ugfelder, 2002;Watts et al, 2004].…”

Section: Discussionmentioning

confidence: 99%

“…This tract has been one of the subjects of interest of our laboratory over the past few years and it has been chosen in this study due to its relatively easy access and dissection and also due to the fact that, as a tract, it is composed of axons and glial cells, and therefore suitable for degeneration studies da Silva et al, 2001].…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural Study of Normal and Degenerating Nerve Fibers in the Protocerebral Tract of the Crab <i>Ucides cordatus</i>

Corrêa¹,

Allodi²,

Martínez³

2005

Brain Behav Evol

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Wallerian degeneration is a very well described phenomenon in the vertebrate nervous system. In arthropods, and especially in crustaceans, nerve fiber degeneration has not been described extensively. In addition, literature shows that the events do not follow the same patterns as in vertebrates. In this study we report, by qualitative and quantitative ultrastructural analyses, the features and time course of the protocerebral tract degeneration following extirpation of the optic stalk. No remarkable changes were observed seven days after lesion. After 28 days the protocerebral tracts presented apparently preserved small and large diameter axons and some degenerating medium axons, with irregular contours and empty-looking aspect of the axoplasm. Forty days after the ablation of the optic stalks, both small (type I) and medium (type II and III) axons revealed signs of partial or total degeneration, but large nerve fibers (type IV) were still intact. After 45 days, the tract showed signs of advanced stage of degeneration and, apart from large axons, normal-looking fibers were almost absent. At these 3 last time points, degenerating axons displayed different electron densities and aspects, probably correlating to different onset times of the process. In addition, cells with granules in their cytoplasm, possibly hemocytes, were quite distinct, especially at 40 and 45 days after axotomy. These cells might share with glial cells the function of phagocytosis of cellular debris during the protocerebral tract degeneration. Quantitative analysis showed that the number of degenerating fibers increased significantly from 28 to 40 days after lesion, whereas the number of normal fibers decreased accordingly. Measurements of cross-sectional areas of normal and degenerating axons showed that types II and III (medium) start to degenerate before type I (small). Type IV (large) axons do not degenerate, even after 40 days. Therefore, we can conclude that degeneration in these afferent fibers starts late after axotomy, but proceeds at a faster rate afterwards until the complete degeneration of small and medium axons.

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“…Sections of the proximal retina/optic ganglia stained with hematoxylin-eosin or reacted with the PAS procedure for glycogen (da Silva et al, 2001) were available for comparisons.…”

Section: Light Microscopymentioning

confidence: 99%

Binding of an antibody against a noncompact myelin protein to presumptive glial cells in the visual system of the crab Ucides cordatus

Silva

Bressan

Cavalcante

et al. 2003

Glia

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Glial cells, in both vertebrate and invertebrate nervous systems, provide an essential environment for developmental, supportive, and physiological functions. However, information on glial cells themselves and on glial cell markers, with the exception of those of Drosophila and other insects, is not abundant in invertebrate organisms. A common ultrastructural feature of invertebrate nervous systems is that layers of glial cell cytoplasm-rich processes ensheath axons and neuronal and glial somata. In the present study, we have examined the binding of a monoclonal antibody to 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in the compound eye and optic lobe of the crab Ucides cordatus using both light and electron microscopy. CNPase is a noncompact myelin protein that is a phenotypic marker of oligodendroglial and Schwann cells, is apparently involved in the ensheathment step prior to myelin compaction, and is also expressed by the potentially myelinating olfactory ensheathing glia. CNPase has raised much interest, first by virtue of its unusual enzymatic activity and more recently by its membrane-skeletal features and possible involvement in migration or expansion of membranes. We have found CNPase-like immunoreactivity in most cells of the compound eye basement membrane and both in optic cartridges of the synaptic layer and cells of the outer sublayer of the lamina ganglionaris. The results suggest that in the crab visual system some, but not all, glial cells, including some adaxonal glia, may express the noncompact myelin protein CNPase or a related protein.

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Crustacean visual system: an investigation on glial cells and their relation to extracellular matrix

Cited by 19 publications

References 33 publications

Novel organization and development of copepod myelin. ii. nonglial origin

Novel organization and development of copepod myelin. ii. nonglial origin

Ultrastructural Study of Normal and Degenerating Nerve Fibers in the Protocerebral Tract of the Crab <i>Ucides cordatus</i>

Binding of an antibody against a noncompact myelin protein to presumptive glial cells in the visual system of the crab Ucides cordatus

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