Quantitative Studies of the Optic Nerve Fiber Layer in the Chicken Retina.

Imagawa, Tomohiro; Fujita, Yūkō; Kitagawa, Hiroshi; Uehara, Masato

doi:10.1292/jvms.61.883

Cited by 8 publications

(7 citation statements)

References 29 publications

(43 reference statements)

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“…In the chicken, myelinated fibers make up 12.5% of the nerve fibers of the optic nerve fiber layer [11]. But it should be emphasized that ION and the retinal optic nerve fiber layer in submammals contain constantly myelinated fibers in some extent.…”

Section: Discussionmentioning

confidence: 99%

Fine Structure of the Retino-Optic Nerve Junction in Dogs

Miyake

Imagawa

Uehara

2004

The Journal of Veterinary Medical Science

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ABSTRACT. In most mammals, the optic nerve fibers are myelinated in its extraocular part (EON) but not in its intraocular part (ION) and also in the retina. Transitional zone from the myelinated to unmyelinated optic nerve usually lies in the central part to the lamina cribrosa. It has been known that dogs contain exceptionally myelinated fibers in ION by light microscopy. The aim of this study was to investigate electron microscopically the retino-optic nerve junction in dogs and re-evaluate the barrier to migration of oligodendroblasts into ION. Fourteen adult dogs were used. EON was largely myelinated. In ION the percentage of myelinated fibers decreased gradually toward the retina. A narrow area of ION adjoining the retina was completely unmyelinated. In most mammalian optic nerves, oligodendrocytes are not found in ION. It has been suggested that oligodendroblasts are prevented from migrating from EON into ION; that is to say, there is a barrier to migration of oligodendroblasts. The lamina cribrosa, a dense meshwork of fibrous astrocytic processes, and a defect in the blood optic nerve barrier have been proposed as a candidate for the barrier to migration. Our results suggest, however, that these factors, at least in dogs, would be not involved in the formation of a barrier to migration of oligodendroblasts. KEY WORDS: astrocytes, canine, electron microscopy, oligodendroblast, retino-optic nerve junction.J. Vet. Med. Sci. 66(12): 1549-1554, 2004 The optic nerve looks like a peripheral nerve in gross anatomy but is comparable with a nerve tract in the central nervous system in terms of embryology and histology. However, it usually contains the connective tissue of the lamina cribrosa and pial septa, whereas the CNS does not principally contain connective tissue [8]. Furthermore, in most mammals, the optic nerve is largely myelinated in the extraocular part (EON) but not in the intraocular part (ION), and the retinal nerve fiber layer is also unmyelinated. In the majority of mammals, a transition zone from myelinated to unmyelinated fibers is located in the central part of the lamina cribrosa, or the scleral canal in animals without a distinct lamina cribrosa [9,10]. In mammals, the optic nerve fibers in ION and the retina are generally thinner than those in EON, and oligodendroblasts can not migrate into ION in embryo.Well known exceptions are the myelinated fibers distributed in the retina and ION in rabbits [3,4], and the myelinated fibers contained in ION in dogs [8,17]. In comparison with the rabbit optic nerve and retina, there are few morphological studies of the optic nerve head and the nerve fiber layer in the retina of dogs, and no electron microscopic observations. The aim of this study was to describe a fine structure of the retinal nerve fiber layer and the optic nerve in dogs with special interest to myelination in the optic nerve fibers. MATERIALS AND METHODSFourteen adult dogs used in the present study were crossbred and medium-sized. Animals were anesthetized with sodium pentobarbital (Nembu...

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Section: Discussionmentioning

confidence: 99%

Fine Structure of the Retino-Optic Nerve Junction in Dogs

Miyake

Imagawa

Uehara

2004

The Journal of Veterinary Medical Science

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“…Investigation into the glycosaminoglycans of the chick eye and research into the potential to disrupt these and the protein constituents of the chick eye without compromising retinal function may similarly enhance the depth and breadth of A3V transduction in the chick retina. It should be noted that the nerve fiber layer, which is located directly under the ILM, may pose an additional barrier to transduction after intravitreal delivery in the chick, as it differs from that of the mouse in being myelinated and substantially thicker 40,41. The substantially larger vitreal volume of the chick globe, namely, ∼40 fold that of the mouse,42 may also hinder intravitreal transduction by diluting injected viral solution and, thus, reducing effective vector titer at retinal cells 43.…”

Section: Discussionmentioning

confidence: 99%

Avian Adeno-Associated Viral Transduction of the Postembryonic Chicken Retina

Waldner

Visser

Fischer

et al. 2019

Trans. Vis. Sci. Tech.

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Purpose: The posthatching chicken is a valuable animal model for research, but molecular tools needed for altering its gene expression are not yet available. Our purpose here was to adapt the adeno-associated viral (AAV) vector method, used widely in mammalian studies, for use in investigations of the chicken retina. We hypothesized that the recently characterized avian AAV (A3V) vector could effectively transduce chick retinal cells for manipulation of gene expression, after intravitreal or subretinal injection. Methods: A3V encoding enhanced green fluorescent protein (EGFP) was injected intravitreally or subretinally into P1-3 chick eye and left for 7 to 10 days. Retinas were then sectioned or flat-mounted and visualized via laser-scanning confocal microscopy for analysis of expression and imaging of retinal cells. Results: Intravitreal A3V-EGFP injection resulted in EGFP expression in a small percent of retinal cells, primarily those with processes and/or cell bodies near the vitreal surface. In contrast, subretinal injection of A3V-EGFP within confined retinal ''blebs'' produced high rates of transduction of rods and all types of cones. Some examples of all other major retinal cell types, including horizontal, amacrine, bipolar, ganglion, and Müller cells, were also transduced, although with much lower frequency than photoreceptors. Conclusions: A3V is a promising tool for investigating chick retinal cells and circuitry in situ. This novel vector can be used for studies in which local photoreceptor transduction is sufficient for meaningful observations. Translational Relevance: With this vector, the postembryonic chick retina can now be used for preclinical trials of gene therapy for prevention and treatment of human retinal disease. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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“…For electron microscopy, the posterior halves of eyes were fixed in a solution of 2% paraformaldehyde and 1% glutaraldehyde for 2 hr or overnight at 4°C, and postfixed with 1% OsO 4 for 1.5 hr [12]. After dehydration through a graded series of alcoholic solutions, pieces of retina were embedded in Epok-812 (Oken, Tokyo, Japan).…”

Section: Methodsmentioning

confidence: 99%

Functional Disorder of the Retina in Manganese-Deficient Japanese Quail Revealed by Electroretinography using a Contact Lens Electrode with Built-In Light Source

Endo

Itoh

Maehara

et al. 2008

The Journal of Veterinary Medical Science

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ABSTRACT. Manganese deficiency results in neurological and skeletal defects, together with ultrastructural disarrangement of the retina in rats. Wild birds show a range of Mn concentrations in their tissues, including the liver, raising the possibility of Mn-related disorders in the wild. Electroretinography (ERG) provides a useful noninvasive approach to evaluate visual function. This method is especially useful in birds, as objective analysis of them is very difficult, while they have well-developed vision. In this study, we carried out a convenient and reliable ERG recording using a contact lens electrode with a built-in light source (LED electrode) of Japanese quail (Coturnix coturnix japonica) fed a Mn-deficient diet. After 10 min light adaptation, single-flash and flicker cone responses were reproducibly recorded to cause an intensity-dependent increase in amplitude of both a-wave and b-wave in single-flash ERG. Mn-deficient feeding markedly decreased the Mn concentration in the liver by almost half in 3 to 6 weeks, followed by body weight loss in 13 to 15 weeks. Implicit time of a-wave and b-wave cone response by single-flash stimulation was significantly delayed in quail with a Mn depletion from 3 to 6 weeks. Every cone response of the Mn-deprived quail had a tendency to decrease amplitude. The ultrastructure of cone photoreceptor cells was disorganized by Mn deficiency, including changes in outer segment discs of photoreceptor cells. These results suggest the essential role of Mn in the integrity of the retinal function of birds. KEY WORDS: cone response, contact lens electrode, electroretinography, Japanese quail, manganese.

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Quantitative Studies of the Optic Nerve Fiber Layer in the Chicken Retina.

Cited by 8 publications

References 29 publications

Fine Structure of the Retino-Optic Nerve Junction in Dogs

Fine Structure of the Retino-Optic Nerve Junction in Dogs

Avian Adeno-Associated Viral Transduction of the Postembryonic Chicken Retina

Functional Disorder of the Retina in Manganese-Deficient Japanese Quail Revealed by Electroretinography using a Contact Lens Electrode with Built-In Light Source

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