Axons from eyes grafted in Xenopus can grow into the spinal cord and reach the optic tectum

Giorgi, P. P.; Loos, H. Van der

doi:10.1038/275746a0

Cited by 75 publications

(13 citation statements)

References 16 publications

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“…When ectopic eyes were transplanted just behind the head along the dorsal midline, axons from transplanted eyes appeared to enter the spinal cord (Giorgi and Van der Loos, 1978;Katz and Lasek, 1978). Furthermore, eye transplantation studies done in Rana pipiens, in which donor tissue was transplanted to the ear position of recipients, generated animals with optic fibres that penetrated the medulla of the host and in some cases exited the brain and established tracts within the spinal cord (Constantine-Paton and Caprianica, 1975;Constantine-Paton and Capranica, 1976a).…”

Section: Discussionmentioning

confidence: 99%

“…Ectopic eyes induced in the cranial region of tadpoles appear to extend 'cellular bridges' and axons towards the optic tecta of the host and these structures are maintained across metamorphosis into adulthood (Harris, 1986;Koo and Graziadei, 1995;Sedohara et al, 2003). When ectopic eyes were transplanted just behind the head along the dorsal midline, axons from transplanted eyes appear to enter the spinal cord of the host, perhaps following the pathways of native Rohon-Beard neurons (Giorgi and Van der Loos, 1978;Katz and Lasek, 1978). However, it is still unknown whether ectopic eyes induced in either the cranial or caudal regions were functional (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Ectopic eyes outside the head inXenopustadpoles provide sensory data for light-mediated learning

Blackiston

Levin

2013

Journal of Experimental Biology

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SUMMARYA major roadblock in the biomedical treatment of human sensory disorders, including blindness, has been an incomplete understanding of the nervous system and its ability to adapt to changes in sensory modality. Likewise, fundamental insight into the evolvability of complex functional anatomies requires understanding brain plasticity and the interaction between the nervous system and body architecture. While advances have been made in the generation of artificial and biological replacement components, the brainʼs ability to interpret sensory information arising from ectopic locations is not well understood. We report the use of eye primordia grafts to create ectopic eyes along the body axis of Xenopus tadpoles. These eyes are morphologically identical to native eyes and can be induced at caudal locations. Cell labeling studies reveal that eyes created in the tail send projections to the stomach and trunk. To assess function we performed light-mediated learning assays using an automated machine vision and environmental control system. The results demonstrate that ectopic eyes in the tail of Xenopus tadpoles could confer vision to the host. Thus ectopic visual organs were functional even when present at posterior locations. These data and protocols demonstrate the ability of vertebrate brains to interpret sensory input from ectopic structures and incorporate them into adaptive behavioral programs. This tractable new model for understanding the robust plasticity of the central nervous system has significant implications for regenerative medicine and sensory augmentation technology.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ectopic eyes outside the head inXenopustadpoles provide sensory data for light-mediated learning

Blackiston

Levin

2013

Journal of Experimental Biology

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“…As the eyes migrate towards each other, a steadily increasing proportion of the monocular field of each eye becomes incorporated into the binocular visual field. Such studies also suggested various possible mechanisms for retinal axon guidance including long-range attraction by the target (Giorgi and van der Loos 1978;Harris 1986) and guidance by local cues (Constantine-Paton and Capranica 1975;Harris 1986). This isthmotectal visual map develops when the eyes move forwards (Udin and Fisher 1985).…”

Section: Development Of Retinotectal Projectionsmentioning

confidence: 99%

“…The ipsilateral retina sends only a sparse direct projection to the tectum (Levine 1980). Sharma 1972;Constantine-Paton and Capranica 1975;Constantine-Paton and Law 1978;Giorgi and van der Loos 1978;Katz and Lasek 1978;Constantine-Paton et al 1983;Harris 1986). Each tectal half receives direct visual input from the entire monocular visual field of the contralateral eye.…”

Section: Development Of Retinotectal Projectionsmentioning

confidence: 99%

Anurans

Donkelaar¹

1998

The Central Nervous System of Vertebrates

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“…In contrast to the ear, the molecular basis of the retinotopic projection of the eye is better understood in terms of Eph and ephrin gradients (Kullander and Klein, 2002;Liu et al, 2016) to set up the chemoaffinity-mediated retinotopic map (Sperry, 1963). In addition, retinal afferents may be attracted to the midbrain as revealed by transplantation of a developing eye onto the spinal cord in Xenopus laevis embryos that showed fibers to reach the midbrain (Giorgi and Van der Loos, 1978). More recent work in transplanting an eye to the trunk demonstrated the ability of afferents to provide successful sensory input into the CNS, but did not reveal how afferent information reached the CNS (Blackiston et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Transplantation of Ears Provides Insights into Inner Ear Afferent Pathfinding Properties

Gordy

Houston

Fritzsch

et al. 2018

Developmental Neurobiology

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Numerous tissue transplantations have demonstrated that otocysts can develop into normal ears in any location in all vertebrates tested thus far, though the pattern of innervation of these transplanted ears has largely been understudied. Here, expanding on previous findings that transplanted ears demonstrate capability of local brainstem innervation and can also be innervated themselves by efferents, we show that inner ear afferents grow toward the spinal cord mostly along existing afferent and efferent fibers and preferentially enter the dorsal spinal cord. Once in the dorsal funiculus of the spinal cord, they can grow toward the hindbrain and can diverge into vestibular nuclei. Inner ear afferents can also project along lateral line afferents. Likewise, lateral line afferents can navigate along inner ear afferents to reach hair cells in the ear. In addition, transplanted ears near the heart show growth of inner ear afferents along epibranchial placode-derived vagus afferents. Our data indicate that inner ear afferents can navigate in foreign locations, likely devoid of any local ear-specific guidance cues, along existing nerves, possibly using the nerve-associated Schwann cells as substrate to grow along. However, within the spinal cord and hindbrain, inner ear afferents can navigate to vestibular targets, likely using gradients of diffusible factors that define the dorso-ventral axis to guide them. Finally, afferents of transplanted ears functionally connect to native hindbrain vestibular circuitry, indicated by eliciting a startle behavior response, and providing excitatory input to specific sets of extraocular motoneurons.

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Axons from eyes grafted in Xenopus can grow into the spinal cord and reach the optic tectum

Cited by 75 publications

References 16 publications

Ectopic eyes outside the head inXenopustadpoles provide sensory data for light-mediated learning

Ectopic eyes outside the head inXenopustadpoles provide sensory data for light-mediated learning

Anurans

Transplantation of Ears Provides Insights into Inner Ear Afferent Pathfinding Properties

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