Retinal projections throughout optic nerve regeneration in the ornate dragon lizard,Ctenophorus ornatus

Dunlop, Sarah; Tran, Ngan Kim; Tee, Lisa; Papadimitriou, John; Beazley, Lyn

doi:10.1002/(sici)1096-9861(20000110)416:2<188::aid-cne5>3.0.co;2-c

Cited by 23 publications

(28 citation statements)

References 63 publications

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“…) and the crush site after only 3 weeks (Dobson, ), which is similar in timing (1 month) to that observed at the crush site of C. ornatus (Dunlop et al. ). Interestingly, the RGC survival capacity in both lizard species was similar (around 70%) despite the fact that transected RGC axons in G. galloti took 6–9 months to reach the optic tectum, which is a considerable delay when compared with the 2 months that crushed axons took in C. ornatus (Lang et al.…”

Section: Introductionsupporting

confidence: 75%

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Regrowth of transected retinal ganglion cell axons despite persistent astrogliosis in the lizard (Gallotia galloti)

et al. 2013

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We analysed the astroglia response that is concurrent with spontaneous axonal regrowth after optic nerve (ON) transection in the lizard Gallotia galloti. At different post-lesional time points (0.5, 1, 3, 6, 9 and 12 months) we used conventional electron microscopy and specific markers for astrocytes [glial fibrillary acidic protein (GFAP), vimentin (Vim), sex-determining region Y-box-9 (Sox9), paired box-2 (Pax2)¸cluster differentiation-44 (CD44)] and for proliferating cells (PCNA). The experimental retina showed a limited glial response since the increase of gliofilaments was not significant when compared with controls, and proliferating cells were undetectable. Conversely, PCNA + cells populated the regenerating ON, optic tract (OTr) and ventricular wall of both the hypothalamus and optic tectum (OT). Subpopulations of these PCNA + cells were identified as GFAP + and Vim + reactive astrocytes and radial glia. Reactive astrocytes up-regulated Vim at 1 month post-lesion, and both Vim and GFAP at 12 months post-lesion in the ON-OTr, indicating long-term astrogliosis. They also expressed Pax2, Sox9 and CD44 in the ON, and Sox9 in the OTr. Concomitantly, persistent tissue cavities and disorganised regrowing fibre bundles reaching the OT were observed. Our ultrastructural data confirm abundant gliofilaments in reactive astrocytes joined by desmosomes. Remarkably, they also accumulated myelin debris and lipid droplets until late stages, indicating their participation in myelin removal. These data suggest that persistent mammalian-like astrogliosis in the adult lizard ON contributes to a permissive structural scaffold for long-term axonal regeneration and provides a useful model to study the molecular mechanisms involved in these beneficial neuron-glia interactions.

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Section: Introductionsupporting

confidence: 75%

“…; Dunlop et al. ). These two axotomy methods offer complementary views of spontaneous central nervous system (CNS) axonal regeneration capacity in vivo .…”

Section: Introductionmentioning

confidence: 97%

Regrowth of transected retinal ganglion cell axons despite persistent astrogliosis in the lizard (Gallotia galloti)

et al. 2013

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“…Similar to V. aspis and G. galloti, axons penetrated the lesion site and reached the contralateral optic tectum but did so more rapidly -that is, by one to two months; regenerating fibers also formed more robust projections compared to V. aspis and G. galloti (Rio et al, 1989;Dunlop et al, 2000;Lang et al, 2002). Figs.…”

Section: % Inmentioning

confidence: 83%

Functional Aspects of Optic Nerve Regeneration in Non‐Mammalian Vertebrates

Dunlop

2006

Model Organisms in Spinal Cord Regeneration

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OverviewOptic nerve regeneration in fish and amphibia is largely successful with return of useful vision within one to two months, but is abortive in birds and mammals, with blindness persisting after nerve injury. Reptiles have an intermediate degree of success, with some species displaying robust regeneration and others only a limited degree. Nevertheless, in all reptiles tested behaviorally to date, animals are blind via the experimental eye. In the lizard Ctenophorus ornatus, although regeneration is robust, it is also highly inaccurate, with axons displaying a range of errors en route to visual targets. Crucially, a topographic map is not restored. Comparison of events in fish and lizard reveals that re-expression of guidance cues and recapitulation of an appropriate balance of excitatory glutamatergic and inhibitory GABAergic neurotransmission are crucial in restoring topography and therefore useful vision. Nevertheless, defects can be overcome by training lizards on a visual task with the result that topography is restored and animals are able to elicit visually elicited behavioral responses.

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“…These obstacles are (1) scar tissue formation after tissue injury [15][16][17][18][19][20][21], (2) gaps in nervous tissue formed during phagocytosis of dying cells after injury [17,[22][23][24][25][26][27][28], (3) factors that inhibit axon growth in the mature mammalian CNS [15,17,[22][23][24][25][26][27][28][29][30][31][32][33][34], and (4) failure of many adult neurons to initiate axonal extension [17,[22][23][24][25][26]29,31,35,36]. Through reducing or overcoming the first two and possibly the first three of the barriers described above and creating a permissive environment for axonal regrowth using a synthetic biologic nanomaterial, with components that break down into beneficial building blocks and produce no adverse effects in the CNS, functional behavioral recovery becomes a reality.…”

Section: Second P: Creating a Permissive Environmentmentioning

confidence: 99%

Nano Neurology and the Four P's of Central Nervous System Regeneration: Preserve, Permit, Promote, Plasticity

Ellis-Behnke

2007

Medical Clinics of North America

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Retinal projections throughout optic nerve regeneration in the ornate dragon lizard,Ctenophorus ornatus

Cited by 23 publications

References 63 publications

Regrowth of transected retinal ganglion cell axons despite persistent astrogliosis in the lizard (Gallotia galloti)

Regrowth of transected retinal ganglion cell axons despite persistent astrogliosis in the lizard (Gallotia galloti)

Functional Aspects of Optic Nerve Regeneration in Non‐Mammalian Vertebrates

Nano Neurology and the Four P's of Central Nervous System Regeneration: Preserve, Permit, Promote, Plasticity

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