The growth and differentiation of the regenerating spinal cord of the lizard, <i>Anolis carolinensis</i>

Egar, Margaret; Simpson, Sidney B.; Singer, Marcus

doi:10.1002/jmor.1051310202

Cited by 89 publications

(42 citation statements)

References 22 publications

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“…Studies carried out on lizards (Egar et al 1970), tailed amphibians (Singer et al 1979; Zhang et al 2000; Mchedlishvili et al 2007), and immature eels (Dervan and Roberts 2003) have revealed the role played by ependymal cells in the healing and reconstruction of the injured spinal cord. Our findings are, in general, coincident with these previous reports.…”

Section: Discussionmentioning

confidence: 99%

Cell proliferation and cytoarchitectural remodeling during spinal cord reconnection in the fresh-water turtle Trachemys dorbignyi

et al. 2011

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In fresh-water turtles, the bridge connecting the proximal and caudal stumps of transected spinal cords consists of regenerating axons running through a glial cellular matrix. To understand the process leading to the generation of the scaffold bridging the lesion, we analyzed the mitotic activity triggered by spinal injury in animals maintained alive for 20–30 days after spinal cord transection. Flow cytometry and bromodeoxyuridine (BrdU)-labeling experiments revealed a significant increment of cycling cells around the lesion epicenter. BrdU-tagged cells maintained a close association with regenerating axons. Most dividing cells expressed the brain lipid-binding protein (BLBP). Cells with BrdU-positive nuclei expressed glial fibrillary acidic protein. As spinal cord regeneration involves dynamic cell rearrangements, we explored the ultra-structure of the bridge and found cells with the aspect of immature oligodendrocytes forming an embryonic-like microenvironment. These cells supported and ensheathed regenerating axons that were recognized by immunocytological and electron-microscopical procedures. Since functional recovery depends on proper impulse transmission, we examined the anatomical axon-glia relationships near the lesion epicenter. Computer-assisted three-dimensional models revealed helical axon-glial junctions in which the intercellular space appeared to be reduced (5–7 nm). Serial-sectioning analysis revealed that fibril-containing processes provided myelinating axon sheaths. Thus, disruption of the ependymal layer elicits mitotic activity predominantly in radial glia expressing BLBP on the lateral aspects of the ependyma. These cycling cells seem to migrate and contribute to the bridge providing the main support and sheaths for regenerating axons.

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Section: Discussionmentioning

confidence: 99%

Cell proliferation and cytoarchitectural remodeling during spinal cord reconnection in the fresh-water turtle Trachemys dorbignyi

et al. 2011

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“…Our group has focused on the process of central nervous system (CNS) reconstruction within the tail regenerate after tail excision. We have examined this phenomenon in the lizard (Simpson, 1968;Egar et al, 1970) and newt (Egar and Singer, 1972;Nordlander and Singer, 1978;Singer et al, 1979;Egar and Singer, 1981). In particular, we have concentrated on patterns of longitudinal tract development.…”

Section: Introductionmentioning

confidence: 99%

Early stages of spinal ganglion formation during tail regeneration in the newt, Notophthalmus viridescens

et al. 1988

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Stages in the development of sensory ganglia in the regenerating newt tail after amputation are described by taking advantage of the rostrocaudal developmental gradient of the regenerating tail. A series of ganglia, beginning at the tip of the regenerate and progressing rostrally, were examined. Eight-week regenerates were used because they showed the most complete array of stages. The first recognizable ganglia appear as small clusters of cells sitting dorsally on the already established ventral roots. The cluster of ganglionic cells steadily expands with the addition of many new cells. Signs of cell differentiation within the ganglion precede the formation of the dorsal root rudiment, which assumes several different configurations but most commonly enters the cord close to the ventral root. Our material suggests that ganglion precursor cells originate in the ventral region of the developing spinal cord and migrate out of the cord by travelling along the ventral root until, at a suitable distance from the cord, they halt, proliferate, and eventually differentiate. In the regenerate, we saw no evidence of neural crest cells--such as those that give rise to ganglia in the trunk region during development--forming at the dorsal region of the regenerated neural tube. Nor was there any morphological evidence of mesenchymal contribution to the ganglion cell clusters.

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“…Upon regeneration, the radial glia of the central canal proliferate and self-organize into the ependymal tube. In turn, the ependymal tube acts as a tract for the outgrowth of descending nerve fibers that sprout from the original cord (13–15). Ascending nerves are not regenerated, no new nerve cell bodies are formed, with the exception of cerebrospinal-fluid-contacting-neurons (CSFCNs) that contribute to the ependymal tube (16).…”

Section: The Regenerated Lizard Tail Nervous System Consists Of Functmentioning

confidence: 99%

Lizard tail regeneration as an instructive model of enhanced healing capabilities in an adult amniote

Lozito

Tuan

2016

Connective Tissue Research

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The ability to regenerate damaged or lost tissues has remained the lofty goal of regenerative medicine. Unfortunately, humans, like most mammals, suffer from very minimal natural regenerative capabilities. Certain non-mammalian animal species, however, are not so limited in their healing capabilities, and several have attracted the attention of researchers hoping to recreate enhanced healing responses in humans. This review focuses on one such animal group with remarkable regenerative abilities, the lizards. As the closest relatives of mammals that exhibit enhanced regenerative abilities as adults, lizards potentially represent the most relevant model for direct comparison and subsequent improvement of mammalian healing. Lizards are able to regenerate amputated tails, and exhibit adaptations that both limit tissue damage in response to injury and initiate coordinated regenerative responses. This review summarizes the salient aspects of lizard tail regeneration as they relate to the overall regenerative process, and also presents the relevant information pertaining to regrowth of specific tissues, including skeletal, muscular, nervous, and vascular tissues. The goal of this review is to introduce the topic of lizard tail regeneration to new audiences with the hope of expanding the knowledge base of this under-utilized but potentially powerful model organism.

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The growth and differentiation of the regenerating spinal cord of the lizard, Anolis carolinensis

Cited by 89 publications

References 22 publications

Cell proliferation and cytoarchitectural remodeling during spinal cord reconnection in the fresh-water turtle Trachemys dorbignyi

Cell proliferation and cytoarchitectural remodeling during spinal cord reconnection in the fresh-water turtle Trachemys dorbignyi

Early stages of spinal ganglion formation during tail regeneration in the newt, Notophthalmus viridescens

Lizard tail regeneration as an instructive model of enhanced healing capabilities in an adult amniote

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