An experimental anatomical study of the optic nerve fibers in the rat: Courses of the accessory optic tract

AbstractThe autoradiographic distribution of [3H]nicotine binding sites was examined in the superior colliculus in normal rats and cats, and in animals in which one or both eyes were removed. [3H]Nicotine binding sites in normal animals were densely concentrated in the superficial layers of the colliculus corresponding to the zone of termination of optic nerve fibers. Following bilateral enucleation, [3H]nicotine binding in the superficial collicular layers was drastically reduced. Unilateral enucleation markedly reduced [3H]nicotine binding sites in the colliculus contralateral to the removed eye, with little effect on the ipsilateral colliculus. These results provide further evidence that nicotinic acetylcholine receptors have a presynaptic location on optic tract terminals and may therefore modulate retinotectal transmission in both the rat and cat visual system.

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Microsurgical Resection of a Chiasmatic Cavernoma: 3-Dimensional Operative Video

Operative Neurosurgery ◽

10.1093/ons/opab063 ◽

2021 ◽

Author(s):

Alvaro Campero ◽

Ignacio Casas-Parera ◽

Juan F Villalonga ◽

Matías Baldoncini

Keyword(s):

Optic Nerve ◽

Visual Field ◽

Visual Loss ◽

Brain Mri ◽

Optic Tract ◽

Nerve Fibers ◽

Visual Field Defects ◽

Cavernous Malformations ◽

Transsylvian Approach ◽

The Right

Abstract According to reports from the literature,1,2 depending on the location where cavernomas appear, range from the very common locations to unusual. Cavernous malformations arising from the optic nerve and chiasm are rare, with only few cases reported to date.3-5 We present a case of a 28-yr-old man who suddenly started with sever visual loss in the right eye and homonymous lateral hemianopia in the left eye. Because of the acute symptomatology, a brain MRI was immediately performed in order to diagnose the etiology. The MRI showed a chiasmatic mass with right extension, heterogeneous on T1 and T2 sequences, without enhancement after gadolinium. The surgery was carried out a week after the diagnosis. A right pterional transsylvian approach was performed and the cavernoma was resected with microsurgical maneuvers, preserving the optic nerve fibers, chiasm, and optic tract. The patient evolved favorably, improving the visual deficit in the postoperative period as can be observed in the postoperative visual field study 7 mo after the surgery. The patient signed an informed consent for the procedure and agreed with the use of his images and surgical video for research and academic purposes. Our surgical case emphasizes the importance of a prompt diagnosis and surgery for chiasmatic cavernomas3 associated to visual loss, providing early decompression of the optic apparatus and improvement of the visual field defects after surgery.

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Electrophysiological study of the posterior accessory optic tract

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1960.199.3.522 ◽

1960 ◽

Vol 199 (3) ◽

pp. 522-528 ◽

Cited By ~ 15

Author(s):

Duco Hamasaki ◽

Elwin Marg

Keyword(s):

Optic Nerve ◽

Superior Colliculus ◽

Electrophysiological Study ◽

Optic Tract ◽

Nerve Fibers ◽

Medial Geniculate ◽

Centrifugal Fiber ◽

Ipsilateral Stimulation ◽

Electrophysiological Methods ◽

Stimulation Of

Electrophysiological methods were used to detect the presence of the posterior accessory optic tract—transpeduncular tract in the rabbit. Photic stimulation gave rise to mainly an ‘on’ response from the contralateral nucleus of the transpeduncular tract. Electrical stimulation of the optic nerve fibers evoked a response from this nucleus with a latency of 1–3 msec. A response could not be elicited from the nucleus of the transpeduncular tract, the lateral geniculate nucleus, or the superior colliculus by ipsilateral stimulation. Encéphale isolé preparations showed that the responses recorded under urethane anesthesia were not altered by the drug. The nucleus of the posterior accessory optic tract is situated between the optic nerve and the nucleus of the transpeduncular tract, and lies on the dorsolateral aspect of the midbrain between the superior colliculus and the medial geniculate nucleus. No centrifugal fiber responses have been found which originate from the nucleus of the transpeduncular tract and pass to the retina via the optic nerve.

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Neural and vascular architecture of the septum pellucidum: an anatomical study and considerations for safe endoscopic septum pellucidotomy

Journal of Neurosurgery ◽

10.3171/2019.5.jns19754 ◽

2020 ◽

Vol 133 (3) ◽

pp. 902-911

Author(s):

Laszlo Barany ◽

Cintia Meszaros ◽

Oliver Ganslandt ◽

Michael Buchfelder ◽

Peter Kurucz

Keyword(s):

Anatomical Study ◽

Nerve Fibers ◽

Septum Pellucidum ◽

Cresyl Violet ◽

Membranous Structure ◽

Luxol Fast Blue ◽

Fast Blue ◽

Frontal Horn ◽

Septal Nuclei ◽

Fiber Dissection

OBJECTIVEThe septum pellucidum is a bilateral thin membranous structure representing the border between the frontal horns of the lateral ventricles. Its most examined components are the septal veins due to their surgical importance during endoscopic septum pellucidotomy (ESP), which is a well-accepted method for surgical treatment of unilateral hydrocephalus. It is widely accepted that the septum pellucidum contains nerve fibers as well, but interestingly, no anatomical study has been addressed to its neural components before. The aim of the present study was to identify these elements as well as their relations to the septal veins and to define major landmarks within the ventricular system for neurosurgical use.METHODSNine formalin-fixed human cadaveric brains (18 septa pellucida) were involved in this study. A central block containing both septa pellucida was removed and frozen at −30°C for 2 weeks in 7 cases. The fibers of the septum pellucidum and the adjacent areas including the venous elements were dissected under magnification by using homemade wooden spatulas and microsurgical instruments. In 2 cases a histological technique was used to validate the findings of the dissections. The blocks were sliced, embedded in paraffin, cut in 7-µm-thick slices, and then stained as follows: 1) with H & E, 2) with Luxol fast blue combined with cresyl violet, and 3) with Luxol fast blue combined with Sirius red.RESULTSThe septum pellucidum and the subjacent septum verum form the medial wall of the frontal horn of the lateral ventricle. Both structures contain nerve fibers that were organized in 3 groups: 1) the precommissural fibers of the fornix; 2) the inferior fascicle; and 3) the superior fascicle of the septum pellucidum. The area directly rostral to the postcommissural column of the fornix consisted of macroscopically identifiable gray matter corresponding to the septal nuclei. The histological examinations validated the findings of the authors’ fiber dissections.CONCLUSIONSThe nerve elements of the septum pellucidum as well as the subjacent septum verum were identified with fiber dissection and verified with histology for the first time. The septal nuclei located just anterior to the fornix and the precommissural fibers of the fornix should be preserved during ESP. Considering the venous anatomy as well as the neural architecture of the septum pellucidum, the fenestration should ideally be placed above the superior edge of the fornix and preferably dorsal to the interventricular foramen.

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Melatonin As a Modulator of Degenerative and Regenerative Signaling Pathways in Injured Retinal Ganglion Cells

Current Pharmaceutical Design ◽

10.2174/1381612825666190829151314 ◽

2019 ◽

Vol 25 (28) ◽

pp. 3057-3073 ◽

Cited By ~ 6

Author(s):

Kobra B. Juybari ◽

Azam Hosseinzadeh ◽

Habib Ghaznavi ◽

Mahboobeh Kamali ◽

Ahad Sedaghat ◽

...

Keyword(s):

Optic Nerve ◽

Mitochondrial Dysfunction ◽

Signaling Pathways ◽

Retinal Ganglion Cells ◽

Molecular Mechanisms ◽

Nitrosative Stress ◽

Ganglion Cells ◽

Axon Growth ◽

Nerve Fibers ◽

Retinal Ganglion

Optic neuropathies refer to the dysfunction or degeneration of optic nerve fibers caused by any reasons including ischemia, inflammation, trauma, tumor, mitochondrial dysfunction, toxins, nutritional deficiency, inheritance, etc. Post-mitotic CNS neurons, including retinal ganglion cells (RGCs) intrinsically have a limited capacity for axon growth after either trauma or disease, leading to irreversible vision loss. In recent years, an increasing number of laboratory evidence has evaluated optic nerve injuries, focusing on molecular signaling pathways involved in RGC death. Trophic factor deprivation (TFD), inflammation, oxidative stress, mitochondrial dysfunction, glutamate-induced excitotoxicity, ischemia, hypoxia, etc. have been recognized as important molecular mechanisms leading to RGC apoptosis. Understanding these obstacles provides a better view to find out new strategies against retinal cell damage. Melatonin, as a wide-spectrum antioxidant and powerful freeradical scavenger, has the ability to protect RGCs or other cells against a variety of deleterious conditions such as oxidative/nitrosative stress, hypoxia/ischemia, inflammatory processes, and apoptosis. In this review, we primarily highlight the molecular regenerative and degenerative mechanisms involved in RGC survival/death and then summarize the possible protective effects of melatonin in the process of RGC death in some ocular diseases including optic neuropathies. Based on the information provided in this review, melatonin may act as a promising agent to reduce RGC death in various retinal pathologic conditions.

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Extracellular Matrix Remodeling in the Retina and Optic Nerve of a Novel Glaucoma Mouse Model

Biology ◽

10.3390/biology10030169 ◽

2021 ◽

Vol 10 (3) ◽

pp. 169

Author(s):

Jacqueline Reinhard ◽

Susanne Wiemann ◽

Sebastian Hildebrandt ◽

Andreas Faissner

Keyword(s):

Extracellular Matrix ◽

Optic Nerve ◽

Protein Tyrosine Phosphatase ◽

Tyrosine Phosphatase ◽

Nerve Fibers ◽

Receptor Protein ◽

Mrna Levels ◽

Protein Tyrosine ◽

Tenascin C ◽

Iop Elevation

Glaucoma is a neurodegenerative disease that is characterized by the loss of retinal ganglion cells (RGC) and optic nerve fibers. Increased age and intraocular pressure (IOP) elevation are the main risk factors for developing glaucoma. Mice that are heterozygous (HET) for the mega-karyocyte protein tyrosine phosphatase 2 (PTP-Meg2) show chronic and progressive IOP elevation, severe RGCs loss, and optic nerve damage, and represent a valuable model for IOP-dependent primary open-angle glaucoma (POAG). Previously, evidence accumulated suggesting that glaucomatous neurodegeneration is associated with the extensive remodeling of extracellular matrix (ECM) molecules. Unfortunately, little is known about the exact ECM changes in the glaucomatous retina and optic nerve. Hence, the goal of the present study was to comparatively explore ECM alterations in glaucomatous PTP-Meg2 HET and control wild type (WT) mice. Due to their potential relevance in glaucomatous neurodegeneration, we specifically analyzed the expression pattern of the ECM glycoproteins fibronectin, laminin, tenascin-C, and tenascin-R as well as the proteoglycans aggrecan, brevican, and members of the receptor protein tyrosine phosphatase beta/zeta (RPTPβ/ζ) family. The analyses were carried out in the retina and optic nerve of glaucomatous PTP-Meg2 HET and WT mice using quantitative real-time PCR (RT-qPCR), immunohistochemistry, and Western blot. Interestingly, we observed increased fibronectin and laminin levels in the glaucomatous HET retina and optic nerve compared to the WT group. RT-qPCR analyses of the laminins α4, β2 and γ3 showed an altered isoform-specific regulation in the HET retina and optic nerve. In addition, an upregulation of tenascin-C and its interaction partner RPTPβ/ζ/phosphacan was found in glaucomatous tissue. However, comparable protein and mRNA levels for tenascin-R as well as aggrecan and brevican were observed in both groups. Overall, our study showed a remodeling of various ECM components in the glaucomatous retina and optic nerve of PTP-Meg2 HET mice. This dysregulation could be responsible for pathological processes such as neovascularization, inflammation, and reactive gliosis in glaucomatous neurodegeneration.

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Fibre organization and reorganization in the retinotectal projection of Xenopus

Development ◽

10.1242/dev.99.3.393 ◽

1987 ◽

Vol 99 (3) ◽

pp. 393-410

Author(s):

J.S. Taylor

Keyword(s):

Optic Nerve ◽

Ganglion Cell ◽

Rana Pipiens ◽

Optic Tract ◽

Retinal Position ◽

Dual Representation ◽

Optic Chiasma ◽

Age Related ◽

Pass Through ◽

Radial Organization

This study concerns the retinotopic organization of the ganglion cell fibres in the visual system of the frog Xenopus laevis. HRP was used to trace the pathways taken by fibres from discrete retinal positions as they pass from the retina, along the optic nerve and into the chiasma. The ganglion cell fibres in the retina are arranged in fascicles which correspond with their circumferential positions of origin. Within the fascicles the fibres show little age-related layering and do not have a strict radial organization. As the fascicles of fibres pass into the optic nerve head there is some exchange of position resulting in some loss of the retinal circumferential organization. The poor radial organization of the fibres in the retinal fascicles persists as the fibres pass through the intraocular part of the nerve. At a position just behind the eye there is a major fibre reorganization in which fibres arising from cells of increasingly peripheral retinal locations are found to have passed into increasingly peripheral positions in the nerve. Thus, fibres from peripheral-most retina are located at the nerve perimeter, whilst fibres from central retina are located in the nerve core. It is at this point that the radial, chronotopic, ordering of the ganglion cell axons, found throughout the rest of the optic pathway, is established. This annular organization persists along the length of the nerve until a position just before the nerve enters the brain. Here, fibres from each annulus move to form layers as they pass into the optic chiasma. This change in the radial organization appears to be related to the pathway followed by all newly growing fibres, in the most superficial part of the optic tract, adjacent to the pia. Just behind the eye, where fibres become radially ordered, the circumferential organization of the projection is largely lost. Fibres from every circumferential retinal position, which are of similar radial position, are distributed within the same annulus of the nerve. At the nerve-chiasma junction where each annulus forms a single layer as it enters the optic tract, there is a further mixing of fibres from all circumferential positions. However, as the fibres pass through the chiasma some active pathway selection occurs, generating the circumferential organization of the fibres in the optic tract. Additional observations of the organization of fibres in the optic nerve of Rana pipiens confirm previous reports of a dual representation of fibres within the nerve. The difference in the organization of fibres in the optic nerve of Xenopus and Rana pipiens is discussed.

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