Biomaterial Database

Anomalous axonal outgrowth at the retina caused by injury to the optic nerve or tectal ablation in adult Xenopus. 1982

R C Bohn, and P J Reier

The retina and optic nerve head have been examined by light and electron microscopy in adult Xenopus laevis after injury to optic nerve fibres. Intraorbital resection, transection or crush of the optic nerve all resulted in the appearance at the retina of a mass of actively growing axons which formed a ring around the intraretinal and adjacent choroidal portions of the optic nerve head. Formation of this heterotopic axon population was first noted at two weeks after nerve injury and fibres persisted for at least six months. The ectopic fibres were separated from the optic nerve head by astrocytes within the retina or by blood vessels and fibroblasts of the leptomeninges at extraretinal locations. In general, the orientation of the ectopic fibres was perpendicular to the fibres of the optic nerve. Bundles of axons were found between the ring of ectopic fibres and the pigment epithelial layer of the retina or among the blood sinuses of the choroid. Similar ectopic fibres were seen following transection of the optic nerve at the chiasm and after tectal ablation although the onset of these changes was slower than that seen after nerve resection. It is concluded that damage to visual pathways in the frog induces dramatic morphological alterations in the optic nerve and retina far proximal to the site of injury in this regenerating system.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009412	Nerve Fibers	Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.	Cerebellar Mossy Fibers,Mossy Fibers, Cerebellar,Cerebellar Mossy Fiber,Mossy Fiber, Cerebellar,Nerve Fiber
D009416	Nerve Regeneration	Renewal or physiological repair of damaged nerve tissue.	Nerve Tissue Regeneration,Nervous Tissue Regeneration,Neural Tissue Regeneration,Nerve Tissue Regenerations,Nervous Tissue Regenerations,Neural Tissue Regenerations,Regeneration, Nerve,Regeneration, Nerve Tissue,Regeneration, Nervous Tissue,Regeneration, Neural Tissue,Tissue Regeneration, Nerve,Tissue Regeneration, Nervous,Tissue Regeneration, Neural
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D009897	Optic Chiasm	The X-shaped structure formed by the meeting of the two optic nerves. At the optic chiasm the fibers from the medial part of each retina cross to project to the other side of the brain while the lateral retinal fibers continue on the same side. As a result each half of the brain receives information about the contralateral visual field from both eyes.	Chiasma Opticum,Optic Chiasma,Optic Decussation,Chiasm, Optic,Chiasma Opticums,Chiasma, Optic,Chiasmas, Optic,Chiasms, Optic,Decussation, Optic,Decussations, Optic,Optic Chiasmas,Optic Chiasms,Optic Decussations,Opticum, Chiasma,Opticums, Chiasma
D009900	Optic Nerve	The 2nd cranial nerve which conveys visual information from the RETINA to the brain. The nerve carries the axons of the RETINAL GANGLION CELLS which sort at the OPTIC CHIASM and continue via the OPTIC TRACTS to the brain. The largest projection is to the lateral geniculate nuclei; other targets include the SUPERIOR COLLICULI and the SUPRACHIASMATIC NUCLEI. Though known as the second cranial nerve, it is considered part of the CENTRAL NERVOUS SYSTEM.	Cranial Nerve II,Second Cranial Nerve,Nervus Opticus,Cranial Nerve, Second,Cranial Nerves, Second,Nerve, Optic,Nerve, Second Cranial,Nerves, Optic,Nerves, Second Cranial,Optic Nerves,Second Cranial Nerves
D010857	Pigment Epithelium of Eye	The layer of pigment-containing epithelial cells in the RETINA; the CILIARY BODY; and the IRIS in the eye.	Eye Pigment Epithelium
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001345	Autoradiography	The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed)	Radioautography