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.Nerve Fibers, Myelinated: A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.Sciatic Nerve: A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.Peripheral Nerves: The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.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.Myelin Sheath: The lipid-rich sheath surrounding AXONS in both the CENTRAL NERVOUS SYSTEMS and PERIPHERAL NERVOUS SYSTEM. The myelin sheath is an electrical insulator and allows faster and more energetically efficient conduction of impulses. The sheath is formed by the cell membranes of glial cells (SCHWANN CELLS in the peripheral and OLIGODENDROGLIA in the central nervous system). Deterioration of the sheath in DEMYELINATING DISEASES is a serious clinical problem.Ranvier's Nodes: Regularly spaced gaps in the myelin sheaths of peripheral axons. Ranvier's nodes allow saltatory conduction, that is, jumping of impulses from node to node, which is faster and more energetically favorable than continuous conduction.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Neural Conduction: The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.Nerve Regeneration: Renewal or physiological repair of damaged nerve tissue.Sural Nerve: A branch of the tibial nerve which supplies sensory innervation to parts of the lower leg and foot.Nerve Fibers, Unmyelinated: A class of nerve fibers as defined by their nerve sheath arrangement. The AXONS of the unmyelinated nerve fibers are small in diameter and usually several are surrounded by a single MYELIN SHEATH. They conduct low-velocity impulses, and represent the majority of peripheral sensory and autonomic fibers, but are also found in the BRAIN and SPINAL CORD.Spinal Nerve Roots: Paired bundles of NERVE FIBERS entering and leaving the SPINAL CORD at each segment. The dorsal and ventral nerve roots join to form the mixed segmental spinal nerves. The dorsal roots are generally afferent, formed by the central projections of the spinal (dorsal root) ganglia sensory cells, and the ventral roots are efferent, comprising the axons of spinal motor and PREGANGLIONIC AUTONOMIC FIBERS.Neurons, Afferent: Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.Nerve Endings: Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS.Retinal Ganglion Cells: Neurons of the innermost layer of the retina, the internal plexiform layer. They are of variable sizes and shapes, and their axons project via the OPTIC NERVE to the brain. A small subset of these cells act as photoreceptors with projections to the SUPRACHIASMATIC NUCLEUS, the center for regulating CIRCADIAN RHYTHM.Schwann Cells: Neuroglial cells of the peripheral nervous system which form the insulating myelin sheaths of peripheral axons.Tibial Nerve: The medial terminal branch of the sciatic nerve. The tibial nerve fibers originate in lumbar and sacral spinal segments (L4 to S2). They supply motor and sensory innervation to parts of the calf and foot.Optic Nerve Diseases: Conditions which produce injury or dysfunction of the second cranial or optic nerve, which is generally considered a component of the central nervous system. Damage to optic nerve fibers may occur at or near their origin in the retina, at the optic disk, or in the nerve, optic chiasm, optic tract, or lateral geniculate nuclei. Clinical manifestations may include decreased visual acuity and contrast sensitivity, impaired color vision, and an afferent pupillary defect.Nerve Crush: Treatment of muscles and nerves under pressure as a result of crush injuries.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Peripheral Nerve Injuries: Injuries to the PERIPHERAL NERVES.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Dietary Fiber: The remnants of plant cell walls that are resistant to digestion by the alimentary enzymes of man. It comprises various polysaccharides and lignins.Muscle Fibers, Skeletal: Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.Nerve Block: Interruption of NEURAL CONDUCTION in peripheral nerves or nerve trunks by the injection of a local anesthetic agent (e.g., LIDOCAINE; PHENOL; BOTULINUM TOXINS) to manage or treat pain.Optic Disk: The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve.Median Nerve: A major nerve of the upper extremity. In humans, the fibers of the median nerve originate in the lower cervical and upper thoracic spinal cord (usually C6 to T1), travel via the brachial plexus, and supply sensory and motor innervation to parts of the forearm and hand.Cochlear Nerve: The cochlear part of the 8th cranial nerve (VESTIBULOCOCHLEAR NERVE). The cochlear nerve fibers originate from neurons of the SPIRAL GANGLION and project peripherally to cochlear hair cells and centrally to the cochlear nuclei (COCHLEAR NUCLEUS) of the BRAIN STEM. They mediate the sense of hearing.Facial Nerve: The 7th cranial nerve. The facial nerve has two parts, the larger motor root which may be called the facial nerve proper, and the smaller intermediate or sensory root. Together they provide efferent innervation to the muscles of facial expression and to the lacrimal and SALIVARY GLANDS, and convey afferent information for TASTE from the anterior two-thirds of the TONGUE and for TOUCH from the EXTERNAL EAR.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.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Sensory Receptor Cells: Specialized afferent neurons capable of transducing sensory stimuli into NERVE IMPULSES to be transmitted to the CENTRAL NERVOUS SYSTEM. Sometimes sensory receptors for external stimuli are called exteroceptors; for internal stimuli are called interoceptors and proprioceptors.Ulnar Nerve: A major nerve of the upper extremity. In humans, the fibers of the ulnar nerve originate in the lower cervical and upper thoracic spinal cord (usually C7 to T1), travel via the medial cord of the brachial plexus, and supply sensory and motor innervation to parts of the hand and forearm.Tomography, Optical Coherence: An imaging method using LASERS that is used for mapping subsurface structure. When a reflective site in the sample is at the same optical path length (coherence) as the reference mirror, the detector observes interference fringes.Spinal Nerves: The 31 paired peripheral nerves formed by the union of the dorsal and ventral spinal roots from each spinal cord segment. The spinal nerve plexuses and the spinal roots are also included.Peripheral Nervous System Diseases: Diseases of the peripheral nerves external to the brain and spinal cord, which includes diseases of the nerve roots, ganglia, plexi, autonomic nerves, sensory nerves, and motor nerves.Nerve Growth Factors: Factors which enhance the growth potentialities of sensory and sympathetic nerve cells.Motor Neurons: Neurons which activate MUSCLE CELLS.Mechanoreceptors: Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.Ganglia, Spinal: Sensory ganglia located on the dorsal spinal roots within the vertebral column. The spinal ganglion cells are pseudounipolar. The single primary branch bifurcates sending a peripheral process to carry sensory information from the periphery and a central branch which relays that information to the spinal cord or brain.Trigeminal Nerve: The 5th and largest cranial nerve. The trigeminal nerve is a mixed motor and sensory nerve. The larger sensory part forms the ophthalmic, mandibular, and maxillary nerves which carry afferents sensitive to external or internal stimuli from the skin, muscles, and joints of the face and mouth and from the teeth. Most of these fibers originate from cells of the TRIGEMINAL GANGLION and project to the TRIGEMINAL NUCLEUS of the brain stem. The smaller motor part arises from the brain stem trigeminal motor nucleus and innervates the muscles of mastication.Spinal Cord: A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.Nerve Degeneration: Loss of functional activity and trophic degeneration of nerve axons and their terminal arborizations following the destruction of their cells of origin or interruption of their continuity with these cells. The pathology is characteristic of neurodegenerative diseases. Often the process of nerve degeneration is studied in research on neuroanatomical localization and correlation of the neurophysiology of neural pathways.Nerve Tissue: Differentiated tissue of the central nervous system composed of NERVE CELLS, fibers, DENDRITES, and specialized supporting cells.Wallerian Degeneration: Degeneration of distal aspects of a nerve axon following injury to the cell body or proximal portion of the axon. The process is characterized by fragmentation of the axon and its MYELIN SHEATH.Ubiquitin Thiolesterase: A thioester hydrolase which acts on esters formed between thiols such as DITHIOTHREITOL or GLUTATHIONE and the C-terminal glycine residue of UBIQUITIN.Ophthalmic Nerve: A sensory branch of the trigeminal (5th cranial) nerve. The ophthalmic nerve carries general afferents from the superficial division of the face including the eyeball, conjunctiva, upper eyelid, upper nose, nasal mucosa, and scalp.Femoral Nerve: A nerve originating in the lumbar spinal cord (usually L2 to L4) and traveling through the lumbar plexus to provide motor innervation to extensors of the thigh and sensory innervation to parts of the thigh, lower leg, and foot, and to the hip and knee joints.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.Radial Nerve: A major nerve of the upper extremity. In humans the fibers of the radial nerve originate in the lower cervical and upper thoracic spinal cord (usually C5 to T1), travel via the posterior cord of the brachial plexus, and supply motor innervation to extensor muscles of the arm and cutaneous sensory fibers to extensor regions of the arm and hand.Nerve Tissue ProteinsNeurofilament Proteins: Type III intermediate filament proteins that assemble into neurofilaments, the major cytoskeletal element in nerve axons and dendrites. They consist of three distinct polypeptides, the neurofilament triplet. Types I, II, and IV intermediate filament proteins form other cytoskeletal elements such as keratins and lamins. It appears that the metabolism of neurofilaments is disturbed in Alzheimer's disease, as indicated by the presence of neurofilament epitopes in the neurofibrillary tangles, as well as by the severe reduction of the expression of the gene for the light neurofilament subunit of the neurofilament triplet in brains of Alzheimer's patients. (Can J Neurol Sci 1990 Aug;17(3):302)Axonal Transport: The directed transport of ORGANELLES and molecules along nerve cell AXONS. Transport can be anterograde (from the cell body) or retrograde (toward the cell body). (Alberts et al., Molecular Biology of the Cell, 3d ed, pG3)Afferent Pathways: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.Mandibular Nerve: A branch of the trigeminal (5th cranial) nerve. The mandibular nerve carries motor fibers to the muscles of mastication and sensory fibers to the teeth and gingivae, the face in the region of the mandible, and parts of the dura.Adrenergic Fibers: Nerve fibers liberating catecholamines at a synapse after an impulse.Nerve Growth Factor: NERVE GROWTH FACTOR is the first of a series of neurotrophic factors that were found to influence the growth and differentiation of sympathetic and sensory neurons. It is comprised of alpha, beta, and gamma subunits. The beta subunit is responsible for its growth stimulating activity.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Demyelinating Diseases: Diseases characterized by loss or dysfunction of myelin in the central or peripheral nervous system.Mineral Fibers: Long, pliable, cohesive natural or manufactured filaments of various lengths. They form the structure of some minerals. The medical significance lies in their potential ability to cause various types of PNEUMOCONIOSIS (e.g., ASBESTOSIS) after occupational or environmental exposure. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p708)Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Glaucoma: An ocular disease, occurring in many forms, having as its primary characteristics an unstable or a sustained increase in the intraocular pressure which the eye cannot withstand without damage to its structure or impairment of its function. The consequences of the increased pressure may be manifested in a variety of symptoms, depending upon type and severity, such as excavation of the optic disk, hardness of the eyeball, corneal anesthesia, reduced visual acuity, seeing of colored halos around lights, disturbed dark adaptation, visual field defects, and headaches. (Dictionary of Visual Science, 4th ed)Calcitonin Gene-Related Peptide: Calcitonin gene-related peptide. A 37-amino acid peptide derived from the calcitonin gene. It occurs as a result of alternative processing of mRNA from the calcitonin gene. The neuropeptide is widely distributed in neural tissue of the brain, gut, perivascular nerves, and other tissue. The peptide produces multiple biological effects and has both circulatory and neurotransmitter modes of action. In particular, it is a potent endogenous vasodilator.Olfactory Nerve: The 1st cranial nerve. The olfactory nerve conveys the sense of smell. It is formed by the axons of OLFACTORY RECEPTOR NEURONS which project from the olfactory epithelium (in the nasal epithelium) to the OLFACTORY BULB.Glossopharyngeal Nerve: The 9th cranial nerve. The glossopharyngeal nerve is a mixed motor and sensory nerve; it conveys somatic and autonomic efferents as well as general, special, and visceral afferents. Among the connections are motor fibers to the stylopharyngeus muscle, parasympathetic fibers to the parotid glands, general and taste afferents from the posterior third of the tongue, the nasopharynx, and the palate, and afferents from baroreceptors and CHEMORECEPTOR CELLS of the carotid sinus.Peripheral Nervous System: The nervous system outside of the brain and spinal cord. The peripheral nervous system has autonomic and somatic divisions. The autonomic nervous system includes the enteric, parasympathetic, and sympathetic subdivisions. The somatic nervous system includes the cranial and spinal nerves and their ganglia and the peripheral sensory receptors.Rana esculenta: An edible species of the family Ranidae, occurring in Europe and used extensively in biomedical research. Commonly referred to as "edible frog".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.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Muscles: Contractile tissue that produces movement in animals.Nociceptors: Peripheral AFFERENT NEURONS which are sensitive to injuries or pain, usually caused by extreme thermal exposures, mechanical forces, or other noxious stimuli. Their cell bodies reside in the DORSAL ROOT GANGLIA. Their peripheral terminals (NERVE ENDINGS) innervate target tissues and transduce noxious stimuli via axons to the CENTRAL NERVOUS SYSTEM.Phrenic Nerve: The motor nerve of the diaphragm. The phrenic nerve fibers originate in the cervical spinal column (mostly C4) and travel through the cervical plexus to the diaphragm.Muscle Fibers, Fast-Twitch: Skeletal muscle fibers characterized by their expression of the Type II MYOSIN HEAVY CHAIN isoforms which have high ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment. Several fast types have been identified.Neurons, Efferent: Neurons which send impulses peripherally to activate muscles or secretory cells.Muscle Fibers, Slow-Twitch: Skeletal muscle fibers characterized by their expression of the Type I MYOSIN HEAVY CHAIN isoforms which have low ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment.Denervation: The resection or removal of the nerve to an organ or part. (Dorland, 28th ed)Vagus Nerve: The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx).Vestibulocochlear Nerve: The 8th cranial nerve. The vestibulocochlear nerve has a cochlear part (COCHLEAR NERVE) which is concerned with hearing and a vestibular part (VESTIBULAR NERVE) which mediates the sense of balance and head position. The fibers of the cochlear nerve originate from neurons of the SPIRAL GANGLION and project to the cochlear nuclei (COCHLEAR NUCLEUS). The fibers of the vestibular nerve arise from neurons of Scarpa's ganglion and project to the VESTIBULAR NUCLEI.Nerve Compression Syndromes: Mechanical compression of nerves or nerve roots from internal or external causes. These may result in a conduction block to nerve impulses (due to MYELIN SHEATH dysfunction) or axonal loss. The nerve and nerve sheath injuries may be caused by ISCHEMIA; INFLAMMATION; or a direct mechanical effect.Substance P: An eleven-amino acid neurotransmitter that appears in both the central and peripheral nervous systems. It is involved in transmission of PAIN, causes rapid contractions of the gastrointestinal smooth muscle, and modulates inflammatory and immune responses.Cotton Fiber: A TEXTILE fiber obtained from the pappus (outside the SEEDS) of cotton plant (GOSSYPIUM). Inhalation of cotton fiber dust over a prolonged period can result in BYSSINOSIS.Sciatic Neuropathy: Disease or damage involving the SCIATIC NERVE, which divides into the PERONEAL NERVE and TIBIAL NERVE (see also PERONEAL NEUROPATHIES and TIBIAL NEUROPATHY). Clinical manifestations may include SCIATICA or pain localized to the hip, PARESIS or PARALYSIS of posterior thigh muscles and muscles innervated by the peroneal and tibial nerves, and sensory loss involving the lateral and posterior thigh, posterior and lateral leg, and sole of the foot. The sciatic nerve may be affected by trauma; ISCHEMIA; COLLAGEN DISEASES; and other conditions. (From Adams et al., Principles of Neurology, 6th ed, p1363)Sympathetic Nervous System: The thoracolumbar division of the autonomic nervous system. Sympathetic preganglionic fibers originate in neurons of the intermediolateral column of the spinal cord and project to the paravertebral and prevertebral ganglia, which in turn project to target organs. The sympathetic nervous system mediates the body's response to stressful situations, i.e., the fight or flight reactions. It often acts reciprocally to the parasympathetic system.Diagnostic Techniques, Ophthalmological: Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.Central Nervous System: The main information-processing organs of the nervous system, consisting of the brain, spinal cord, and meninges.Axotomy: Transection or severing of an axon. This type of denervation is used often in experimental studies on neuronal physiology and neuronal death or survival, toward an understanding of nervous system disease.Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Capsaicin: An alkylamide found in CAPSICUM that acts at TRPV CATION CHANNELS.Cranial Nerves: Twelve pairs of nerves that carry general afferent, visceral afferent, special afferent, somatic efferent, and autonomic efferent fibers.Neuroglia: The non-neuronal cells of the nervous system. They not only provide physical support, but also respond to injury, regulate the ionic and chemical composition of the extracellular milieu, participate in the BLOOD-BRAIN BARRIER and BLOOD-RETINAL BARRIER, form the myelin insulation of nervous pathways, guide neuronal migration during development, and exchange metabolites with neurons. Neuroglia have high-affinity transmitter uptake systems, voltage-dependent and transmitter-gated ion channels, and can release transmitters, but their role in signaling (as in many other functions) is unclear.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Decapodiformes: A superorder of CEPHALOPODS comprised of squid, cuttlefish, and their relatives. Their distinguishing feature is the modification of their fourth pair of arms into tentacles, resulting in 10 limbs.Histocytochemistry: Study of intracellular distribution of chemicals, reaction sites, enzymes, etc., by means of staining reactions, radioactive isotope uptake, selective metal distribution in electron microscopy, or other methods.Microscopy, Electron, Transmission: Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen.Lingual Nerve: A sensory branch of the MANDIBULAR NERVE, which is part of the trigeminal (5th cranial) nerve. The lingual nerve carries general afferent fibers from the anterior two-thirds of the tongue, the floor of the mouth, and the mandibular gingivae.Growth Cones: Bulbous enlargement of the growing tip of nerve axons and dendrites. They are crucial to neuronal development because of their pathfinding ability and their role in synaptogenesis.Cell Count: The number of CELLS of a specific kind, usually measured per unit volume or area of sample.Optic Nerve Injuries: Injuries to the optic nerve induced by a trauma to the face or head. These may occur with closed or penetrating injuries. Relatively minor compression of the superior aspect of orbit may also result in trauma to the optic nerve. Clinical manifestations may include visual loss, PAPILLEDEMA, and an afferent pupillary defect.Electrophysiology: The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Oligodendroglia: A class of large neuroglial (macroglial) cells in the central nervous system. Oligodendroglia may be called interfascicular, perivascular, or perineuronal (not the same as SATELLITE CELLS, PERINEURONAL of GANGLIA) according to their location. They form the insulating MYELIN SHEATH of axons in the central nervous system.Birefringence: The property of nonisotropic media, such as crystals, whereby a single incident beam of light traverses the medium as two beams, each plane-polarized, the planes being at right angles to each other. (Cline et al., Dictionary of Visual Science, 4th ed)Reflex: An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.Efferent Pathways: Nerve structures through which impulses are conducted from a nerve center toward a peripheral site. Such impulses are conducted via efferent neurons (NEURONS, EFFERENT), such as MOTOR NEURONS, autonomic neurons, and hypophyseal neurons.Recurrent Laryngeal Nerve: Branches of the vagus (tenth cranial) nerve. The recurrent laryngeal nerves originate more caudally than the superior laryngeal nerves and follow different paths on the right and left sides. They carry efferents to all muscles of the larynx except the cricothyroid and carry sensory and autonomic fibers to the laryngeal, pharyngeal, tracheal, and cardiac regions.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Synapses: Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.Myelin Proteins: MYELIN-specific proteins that play a structural or regulatory role in the genesis and maintenance of the lamellar MYELIN SHEATH structure.Ophthalmoscopy: Examination of the interior of the eye with an ophthalmoscope.Rana pipiens: A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.Tetrodotoxin: An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.Microscopy, Confocal: A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.Visual Field Tests: Method of measuring and mapping the scope of vision, from central to peripheral of each eye.Animals, Newborn: Refers to animals in the period of time just after birth.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Diabetic Neuropathies: Peripheral, autonomic, and cranial nerve disorders that are associated with DIABETES MELLITUS. These conditions usually result from diabetic microvascular injury involving small blood vessels that supply nerves (VASA NERVORUM). Relatively common conditions which may be associated with diabetic neuropathy include third nerve palsy (see OCULOMOTOR NERVE DISEASES); MONONEUROPATHY; mononeuropathy multiplex; diabetic amyotrophy; a painful POLYNEUROPATHY; autonomic neuropathy; and thoracoabdominal neuropathy. (From Adams et al., Principles of Neurology, 6th ed, p1325)Sodium Channels: Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Myelin Basic Protein: An abundant cytosolic protein that plays a critical role in the structure of multilamellar myelin. Myelin basic protein binds to the cytosolic sides of myelin cell membranes and causes a tight adhesion between opposing cell membranes.Visual Fields: The total area or space visible in a person's peripheral vision with the eye looking straightforward.Stress Fibers: Bundles of actin filaments (ACTIN CYTOSKELETON) and myosin-II that span across the cell attaching to the cell membrane at FOCAL ADHESIONS and to the network of INTERMEDIATE FILAMENTS that surrounds the nucleus.Hindlimb: Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)Ganglia: Clusters of multipolar neurons surrounded by a capsule of loosely organized CONNECTIVE TISSUE located outside the CENTRAL NERVOUS SYSTEM.Trochlear Nerve: The 4th cranial nerve. The trochlear nerve carries the motor innervation of the superior oblique muscles of the eye.Models, Neurological: Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.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.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Scanning Laser Polarimetry: A technique of diagnostic imaging of RETINA or CORNEA of the human eye involving the measurement and interpretation of polarizing ELECTROMAGNETIC WAVES such as radio or light waves. It is helpful in the diagnosis of GLAUCOMA; MACULAR DEGENERATION; and other retinal disorders.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Sensation: The process in which specialized SENSORY RECEPTOR CELLS transduce peripheral stimuli (physical or chemical) into NERVE IMPULSES which are then transmitted to the various sensory centers in the CENTRAL NERVOUS SYSTEM.Oculomotor Nerve: The 3d cranial nerve. The oculomotor nerve sends motor fibers to the levator muscles of the eyelid and to the superior rectus, inferior rectus, and inferior oblique muscles of the eye. It also sends parasympathetic efferents (via the ciliary ganglion) to the muscles controlling pupillary constriction and accommodation. The motor fibers originate in the oculomotor nuclei of the midbrain.Accessory Nerve: The 11th cranial nerve which originates from NEURONS in the MEDULLA and in the CERVICAL SPINAL CORD. It has a cranial root, which joins the VAGUS NERVE (10th cranial) and sends motor fibers to the muscles of the LARYNX, and a spinal root, which sends motor fibers to the TRAPEZIUS and the sternocleidomastoid muscles.Synaptic Transmission: The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.Purkinje Fibers: Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.Neuromuscular Junction: The synapse between a neuron and a muscle.Splanchnic Nerves: The major nerves supplying sympathetic innervation to the abdomen. The greater, lesser, and lowest (or smallest) splanchnic nerves are formed by preganglionic fibers from the spinal cord which pass through the paravertebral ganglia and then to the celiac ganglia and plexuses. The lumbar splanchnic nerves carry fibers which pass through the lumbar paravertebral ganglia to the mesenteric and hypogastric ganglia.Intraocular Pressure: The pressure of the fluids in the eye.Kv1.1 Potassium Channel: A delayed rectifier subtype of shaker potassium channels that is commonly mutated in human episodic ATAXIA and MYOKYMIA.Mucuna: A plant genus of the family FABACEAE that is the source of mucuna gum.Peroneal Nerve: The lateral of the two terminal branches of the sciatic nerve. The peroneal (or fibular) nerve provides motor and sensory innervation to parts of the leg and foot.Mice, Neurologic Mutants: Mice which carry mutant genes for neurologic defects or abnormalities.Cell Adhesion Molecules, Neuronal: Surface ligands that mediate cell-to-cell adhesion and function in the assembly and interconnection of the vertebrate nervous system. These molecules promote cell adhesion via a homophilic mechanism. These are not to be confused with NEURAL CELL ADHESION MOLECULES, now known to be expressed in a variety of tissues and cell types in addition to nervous tissue.Neurilemma: The outermost cytoplasmic layer of the SCHWANN CELLS covering NERVE FIBERS.Maxillary Nerve: The intermediate sensory division of the trigeminal (5th cranial) nerve. The maxillary nerve carries general afferents from the intermediate region of the face including the lower eyelid, nose and upper lip, the maxillary teeth, and parts of the dura.Lasers: An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.Nervous System: The entire nerve apparatus, composed of a central part, the brain and spinal cord, and a peripheral part, the cranial and spinal nerves, autonomic ganglia, and plexuses. (Stedman, 26th ed)Histological Techniques: Methods of preparing tissue for examination and study of the origin, structure, function, or pathology.Saxitoxin: A compound that contains a reduced purine ring system but is not biosynthetically related to the purine alkaloids. It is a poison found in certain edible mollusks at certain times; elaborated by GONYAULAX and consumed by mollusks, fishes, etc. without ill effects. It is neurotoxic and causes RESPIRATORY PARALYSIS and other effects in MAMMALS, known as paralytic SHELLFISH poisoning.Mossy Fibers, Hippocampal: Axons of certain cells in the DENTATE GYRUS. They project to the polymorphic layer of the dentate gyrus and to the proximal dendrites of PYRAMIDAL CELLS of the HIPPOCAMPUS. These mossy fibers should not be confused with mossy fibers that are cerebellar afferents (see NERVE FIBERS).N-Acylsphingosine Galactosyltransferase: An enzyme that catalyzes the conversion of UDP-galactose and N-acylsphingosine to D-galactosylceramide and UDP.Vasoactive Intestinal Peptide: A highly basic, 28 amino acid neuropeptide released from intestinal mucosa. It has a wide range of biological actions affecting the cardiovascular, gastrointestinal, and respiratory systems and is neuroprotective. It binds special receptors (RECEPTORS, VASOACTIVE INTESTINAL PEPTIDE).Horseradish Peroxidase: An enzyme isolated from horseradish which is able to act as an antigen. It is frequently used as a histochemical tracer for light and electron microscopy. Its antigenicity has permitted its use as a combined antigen and marker in experimental immunology.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Thiolester HydrolasesGlaucoma, Open-Angle: Glaucoma in which the angle of the anterior chamber is open and the trabecular meshwork does not encroach on the base of the iris.Receptors, Nerve Growth Factor: Cell surface receptors that bind NERVE GROWTH FACTOR; (NGF) and a NGF-related family of neurotrophic factors that includes neurotrophins, BRAIN-DERIVED NEUROTROPHIC FACTOR and CILIARY NEUROTROPHIC FACTOR.Chorda Tympani Nerve: A branch of the facial (7th cranial) nerve which passes through the middle ear and continues through the petrotympanic fissure. The chorda tympani nerve carries taste sensation from the anterior two-thirds of the tongue and conveys parasympathetic efferents to the salivary glands.Contactin 2: A contactin subtype that plays a role in axon outgrowth, axon fasciculation, and neuronal migration.Anura: An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.Contactins: A family of immunoglobulin-related cell adhesion molecules that are involved in NERVOUS SYSTEM patterning.Rhizotomy: Surgical interruption of a spinal or cranial nerve root. (From Dorland, 28th ed)Dental Pulp: A richly vascularized and innervated connective tissue of mesodermal origin, contained in the central cavity of a tooth and delimited by the dentin, and having formative, nutritive, sensory, and protective functions. (Jablonski, Dictionary of Dentistry, 1992)Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.GAP-43 Protein: A nervous tissue specific protein which is highly expressed in NEURONS during development and NERVE REGENERATION. It has been implicated in neurite outgrowth, long-term potentiation, SIGNAL TRANSDUCTION, and NEUROTRANSMITTER release. (From Neurotoxicology 1994;15(1):41-7) It is also a substrate of PROTEIN KINASE C.Thoracic Nerves: The twelve spinal nerves on each side of the thorax. They include eleven INTERCOSTAL NERVES and one subcostal nerve. Both sensory and motor, they supply the muscles and skin of the thoracic and abdominal walls.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Cochlear Nucleus: The brain stem nucleus that receives the central input from the cochlear nerve. The cochlear nucleus is located lateral and dorsolateral to the inferior cerebellar peduncles and is functionally divided into dorsal and ventral parts. It is tonotopically organized, performs the first stage of central auditory processing, and projects (directly or indirectly) to higher auditory areas including the superior olivary nuclei, the medial geniculi, the inferior colliculi, and the auditory cortex.Neuropeptides: Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells.Receptor, Nerve Growth Factor: A low affinity receptor that binds NERVE GROWTH FACTOR; BRAIN-DERIVED NEUROTROPHIC FACTOR; NEUROTROPHIN 3; and neurotrophin 4.Mice, Inbred C57BLAging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.Neurofibrils: The delicate interlacing threads, formed by aggregations of neurofilaments and neurotubules, coursing through the CYTOPLASM of the body of a NEURON and extending from one DENDRITE into another or into the AXON.Presynaptic Terminals: The distal terminations of axons which are specialized for the release of neurotransmitters. Also included are varicosities along the course of axons which have similar specializations and also release transmitters. Presynaptic terminals in both the central and peripheral nervous systems are included.Hyperalgesia: An increased sensation of pain or discomfort produced by mimimally noxious stimuli due to damage to soft tissue containing NOCICEPTORS or injury to a peripheral nerve.Retinal Neurons: Nerve cells of the RETINA in the pathway of transmitting light signals to the CENTRAL NERVOUS SYSTEM. They include the outer layer of PHOTORECEPTOR CELLS, the intermediate layer of RETINAL BIPOLAR CELLS and AMACRINE CELLS, and the internal layer of RETINAL GANGLION CELLS.Charcot-Marie-Tooth Disease: A hereditary motor and sensory neuropathy transmitted most often as an autosomal dominant trait and characterized by progressive distal wasting and loss of reflexes in the muscles of the legs (and occasionally involving the arms). Onset is usually in the second to fourth decade of life. This condition has been divided into two subtypes, hereditary motor and sensory neuropathy (HMSN) types I and II. HMSN I is associated with abnormal nerve conduction velocities and nerve hypertrophy, features not seen in HMSN II. (Adams et al., Principles of Neurology, 6th ed, p1343)Pain: An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS.Evoked Potentials: Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported.Muscle Spindles: Skeletal muscle structures that function as the MECHANORECEPTORS responsible for the stretch or myotactic reflex (REFLEX, STRETCH). They are composed of a bundle of encapsulated SKELETAL MUSCLE FIBERS, i.e., the intrafusal fibers (nuclear bag 1 fibers, nuclear bag 2 fibers, and nuclear chain fibers) innervated by SENSORY NEURONS.Cholinergic Fibers: Nerve fibers liberating acetylcholine at the synapse after an impulse.Dendrites: Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.Fluorescent Antibody Technique: Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.Abducens Nerve: The 6th cranial nerve which originates in the ABDUCENS NUCLEUS of the PONS and sends motor fibers to the lateral rectus muscles of the EYE. Damage to the nerve or its nucleus disrupts horizontal eye movement control.Autonomic Agents: Agents affecting the function of, or mimicking the actions of, the autonomic nervous system and thereby having an effect on such processes as respiration, circulation, digestion, body temperature regulation, certain endocrine gland secretions, etc.Thermosensing: The sensation of cold, heat, coolness, and warmth as detected by THERMORECEPTORS.Sensory Thresholds: The minimum amount of stimulus energy necessary to elicit a sensory response.Merkel Cells: Modified epidermal cells located in the stratum basale. They are found mostly in areas where sensory perception is acute, such as the fingertips. Merkel cells are closely associated with an expanded terminal bulb of an afferent myelinated nerve fiber. Do not confuse with Merkel's corpuscle which is a combination of a neuron and an epidermal cell.Tongue: A muscular organ in the mouth that is covered with pink tissue called mucosa, tiny bumps called papillae, and thousands of taste buds. The tongue is anchored to the mouth and is vital for chewing, swallowing, and for speech.Neuralgia: Intense or aching pain that occurs along the course or distribution of a peripheral or cranial nerve.Neuropeptide Y: A 36-amino acid peptide present in many organs and in many sympathetic noradrenergic neurons. It has vasoconstrictor and natriuretic activity and regulates local blood flow, glandular secretion, and smooth muscle activity. The peptide also stimulates feeding and drinking behavior and influences secretion of pituitary hormones.Neuroma: A tumor made up of nerve cells and nerve fibers. (Dorland, 27th ed)Kv1.2 Potassium Channel: A delayed rectifier subtype of shaker potassium channels that is selectively inhibited by a variety of SCORPION VENOMS.Cerebellum: The part of brain that lies behind the BRAIN STEM in the posterior base of skull (CRANIAL FOSSA, POSTERIOR). It is also known as the "little brain" with convolutions similar to those of CEREBRAL CORTEX, inner white matter, and deep cerebellar nuclei. Its function is to coordinate voluntary movements, maintain balance, and learn motor skills.Facial Nerve Injuries: Traumatic injuries to the facial nerve. This may result in FACIAL PARALYSIS, decreased lacrimation and salivation, and loss of taste sensation in the anterior tongue. The nerve may regenerate and reform its original pattern of innervation, or regenerate aberrantly, resulting in inappropriate lacrimation in response to gustatory stimuli (e.g., "crocodile tears") and other syndromes.Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Tetraethylammonium CompoundsMicroscopy, Immunoelectron: Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.Macaca fascicularis: A species of the genus MACACA which typically lives near the coast in tidal creeks and mangrove swamps primarily on the islands of the Malay peninsula.
... that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system. The ... axons are myelinated by oligodendrocytes, thus lack neurolemma. The myelin sheaths of Oligodendrocytes do not have neurolemma ... Neurolemma serves a protective function for peripheral nerve fibers. Damaged nerve fibers may regenerate if the perikaryon is ... The neurolemma forms a regeneration tube through which the growing axon reestablishes its original connection. A neurilemoma is ...
Unmyelinated fibers and myelinated axons of the mammalian central nervous system do not regenerate. Some studies have revealed ... However, the myelin layer does not ensure a perfect regeneration of the nerve fiber. Some regenerated nerve fibers do not find ... Myelinated axons are white; hence, the "white matter" of the brain. Myelin insulates axons from electrically charged atoms and ... Along unmyelinated fibers, impulses continuously move as waves, but, in myelinated fibers, they "hop" or propagate by saltatory ...
Therefore, in a myelinated nerve fiber, a large number of molecular bonds are ordered around a radial axis of symmetry. Such a ... densely compacted phospholipid bilayers are spirally rolled up around the cylindrical axons. The linear acyl chains of the ...
... expression of integrins and the rate of regeneration of myelinated nerve fibers. In addition, GHK also increased axon count and ... demonstrated that GHK promotes nerve regeneration. Axon regeneration was studied using collagen tubes with incorporated ... GHK increased migration of hematogenous cells into collagen tube, production of nerve growth factors, ... "Initial upregulation of growth factors and inflammatory mediators during nerve regeneration in the presence of cell adhesive ...
... which are often bundled together in what are called nerve fiber tracts. A myelinated axon is wrapped in a fatty insulating ... There are also unmyelinated axons). Myelin is white, making parts of the brain filled exclusively with nerve fibers appear as ... They send these signals by means of an axon, which is a thin protoplasmic fiber that extends from the cell body and projects, ... These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal ...
The Ib afferent axon is a large diameter, myelinated axon. Each neurotendinous spindle is enclosed in a fibrous capsule which ... Each tendon organ is innervated by a single afferent type Ib sensory nerve fiber (Aɑ fiber) that branches and terminates as ... As a result, the Ib axon is depolarized and fires nerve impulses that are propagated to the spinal cord. The action potential ... The body of the organ is made up of strands of collagen that are connected at one end to the muscle fibers and at the other ...
... nerve fiber). In the peripheral nervous system (PNS) axons can be either myelinated or unmyelinated. Myelination refers to the ... These pockets, or "incisures", can subdivide the myelinated axon into irregular portions. These staggered clefts also provide ... but due to imperfect nature of the process by which Schwann cells wrap the nerve axon, this wrapping process can sometimes ... insulation of an axon with concentric surrounding layers of lipid membrane (myelin) produced by Schwann cells. These layers are ...
Nerves in the PNS consist of many axons myelinated by Schwann cells. If damage occurs to a nerve, the Schwann cells will aid in ... influencing transcriptional cascades and shaping the morphology of the myelinated nerve fibers. Schwann cells are involved in ... If Schwann cells are prevented from associating with axons, the axons die. Regenerating axons will not reach any target unless ... both myelinated and unmyelinated) alive. In myelinated axons, Schwann cells form the myelin sheath. The sheath is not ...
Experimental observations utilizing threshold measurements to assess excitability of myelinated nerve fibers have indicated ... Changes in the geometry of the nerve due to loss of axons within the peripheral nerve likely cause this shift in rheobase. A ... Nerve excitability studies have established a number of biophysical differences between human sensory and motor axons. Even ... 1983) "The spatial distribution of excitability and membrane current in normal and demyelinated mammalian nerve fibers". The ...
Hartline DK, Colman DR (2007). "Rapid conduction and the evolution of giant axons and myelinated fibers". Curr. Biol. 17 (1): ... Huxley A (1949). "Direct determination of membrane resting potential and action potential in single myelinated nerve fibers". ... in a myelinated frog axon and an unmyelinated squid giant axon, but the frog axon has a roughly 30-fold smaller diameter and ... Huxley A (1949). "Evidence for saltatory conduction in peripheral myelinated nerve-fibers". Journal of Physiology. 108 (3): 315 ...
Unmyelinated fibers and myelinated axons of the mammalian central nervous system do not regenerate.[citation needed] ... However, the myelin layer does not ensure a perfect regeneration of the nerve fiber. Some regenerated nerve fibers do not find ... non-myelinated axons (or intermittently myelinated axons, meaning axons with long non-myelinated regions between myelinated ... are passed along the axon.[1] The myelinated axon can be likened to an electrical wire (the axon) with insulating material ( ...
Both the peripheral process and the axon are myelinated. In humans, there are on average 30,000 nerve fibers within the ... The cochlear nerve (also auditory or acoustic nerve) is one of two parts of the vestibulocochlear nerve, a cranial nerve ... has an average of 50,000 fibers. The peripheral axons of auditory nerve fibers form synaptic connections with the hair cells of ... Each type I axon innervates only a single inner hair cell, but each inner hair cell is innervated by up to 30 such nerve fibers ...
... group A nerve fibers, group B nerve fibers, and group C nerve fibers. Groups A and B are myelinated, and group C are ... An axon (from Greek ἄξων áxōn, axis) or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that typically ... Bundles of myelinated axons make up the nerve tracts in the CNS. Where these tracts cross the midline of the brain to connect ... Along myelinated nerve fibers, gaps in the myelin sheath known as nodes of Ranvier occur at evenly spaced intervals. The ...
... are specific to each individual and depend largely on an axon's diameter and the degree to which that axon is myelinated, but ... Two primary classifications exist: demyelinating (Schwann cell damage) and axonal (direct nerve fiber damage). Each of these ... Nerve conduction velocity is an important aspect of nerve conduction studies. It is the speed at which an electrochemical ... Normal impulses in peripheral nerves of the legs travel at 40-45 m/s, and 50-65 m/s in peripheral nerves of the arms. Largely ...
... myelinated axons with moderate conduction velocities, defined as the speed at which a nerve signal travels (2 to 30 m/s). Like ... An A delta fiber, alpha delta fiber, or Aδ fiber is an afferent nerve fiber of a nociceptor. Aδ fibers carry cold, pressure and ... more thickly myelinated group A nerve fibers. The fibers terminate at Rexed laminae I and V. Aδ fibers are thin (2 to 5 μm in ... Because Aδ fibers are thinly myelinated, they send impulses faster than unmyelinated C fibers, but more slowly than other, ...
Group B nerve fibers are axons, which are moderately myelinated, which means less myelinated than group A nerve fibers, and ... more myelinated than group C nerve fibers. Their conduction velocity is 3 to 14 m/s. They are usually general visceral afferent ... fibers and preganglionic nerve fibres of the autonomic nervous system.. ...
Microneurography is a technique using metal electrodes to observe neural traffic of both myelinated and unmyelinated axons in ... and nerve fibers at the dorsal roots (IV fiber). These fibers carry sensory information. Damage or injury to nerve fibers ... C fibers are one class of nerve fiber found in the nerves of the somatic sensory system. They are afferent fibers, conveying ... A nerve fibers B nerve fibers Free nerve ending Nociceptor Pain and nociception Sensory neuron Thermoreceptor Purves, Dale; et. ...
... whereas a single nerve fiber innervates many outer hair cells. Inner hair cell nerve fibers are also very heavily myelinated, ... Efferent synapses occur on outer hair cells and on afferent axons under inner hair cells. The presynaptic terminal bouton is ... Nerve fiber innervation is much denser for inner hair cells than for outer hair cells. A single inner hair cell is innervated ... "Cranial Nerve VIII. Vestibulocochlear Nerve". Meddean. Loyola University Chicago. Retrieved 2008-06-04. Edge AS, Chen ZY (2008 ...
Nerve conduction studies and electromyography are commonly used to evaluate large myelinated sensory and motor nerve fibers, ... Quantitative sudomotor axon reflex testing (QSART) measures sweating response at local body sites to evaluate the small nerve ... These fibers, categorized as C fibers and small Aδ fibers, are present in skin, peripheral nerves, and organs. The role of ... including the trigeminal nerve or occipital nerve[disambiguation needed]. Patients with Fabry disease have isolated small fiber ...
Waxman, S.; Ritchie, J. (1985). "Organization of ion channels in the myelinated nerve fiber". Science. 228 (4707): 1502-1507. ... Waxman, S. G.; Ritchie, J. M. (1993). "Molecular dissection of the myelinated axon". Annals of Neurology. 33 (2): 121-136. doi: ... In 1954 he turned his attention to the properties of mammalian non-myelinated nerve fibres, and since then has made many ... binding of tetrodotoxin has provided new information about the density of sodium channels in various types of nerve." Ritchie ...
Hartline DK, Colman DR (2007). "Rapid conduction and the evolution of giant axons and myelinated fibers". Curr. Biol. 17 (1): ... Main article: Nerve conduction velocity. The action potential generated at the axon hillock propagates as a wave along the axon ... in a myelinated frog axon and an unmyelinated squid giant axon, but the frog axon has a roughly 30-fold smaller diameter and ... As an action potential (nerve impulse) travels down an axon there is a change in polarity across the membrane of the axon. In ...
... compared to a myelinated human neural fiber which conducts at around 120 meters per second. While nerve nets use hormones, the ... In a typical unmyelinated axon, the action potential is conducted at a rate of about 5 meters per second, ... Nerve nets can provide animals with the ability to sense objects through the use of the sensory neurons within the nerve net. ... On the other hand, sea stars, which are echinoderms, have a nerve net in each arm, connected by a central radial nerve ring at ...
... which are often bundled together in what are called nerve fiber tracts. A myelinated axon is wrapped in a fatty insulating ... There are also unmyelinated axons). Myelin is white, making parts of the brain filled exclusively with nerve fibers appear as ... These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal ... Axons transmit signals to other neurons by means of specialized junctions called synapses. A single axon may make as many as ...
A nerve is an enclosed, cable-like bundle of axons (nerve fibers, the long and slender projections of neurons) in the ... carried by the individual neurons that make up the nerve. These impulses are extremely fast, with some myelinated neurons ... Each nerve is a cordlike structure containing bundles of axons. Within a nerve, each axon is surrounded by a layer of ... and bundles of afferent fibers are known as sensory nerves. An efferent nerve fiber conducts signals from a motor neuron in the ...
In addition, patients typically lack unmyelinated and small myelinated nerve fibers in the dorsal root ganglion. Both are ... NTRK1 is a receptor for nerve growth factor (NGF). This protein induces outgrowth of axons and dendrites and promotes the ... CIPA is caused by a genetic mutation which prevents the formation of nerve cells which are responsible for transmitting signals ... and results of nerve conduction studies". Am. J. Med. Genet. 92 (5): 353-60. doi:10.1002/1096-8628(20000619)92:5. 3.0.CO;2-C. ...
... s have Aα axons, which are large-caliber, heavily myelinated fibers that conduct action potentials rapidly. ... some of which contain the cell bodies of neurons belonging to the cranial nerves. Not all cranial nerve nuclei contain α-MNs; ... By contrast, gamma motor neurons have Aγ axons, which are slender, lightly myelinated fibers that conduct less rapidly. ... Alpha motor neurons send fibers that mainly synapse on extrafusal muscle fibers. Other fibers from α-MNs synapse on Renshaw ...
View this Crosssection Of A Nerve Fiber In Intestinal Connective Tissue Showing Both Myelinated And Unmyelinated Axons Tem ... Cross-section of a nerve fiber in intestinal connective tissue showing both myelinated and unmyelinated axons. TEM X47,000. ...
Myelinated fibers and axons distribution in phrenic nerve of male and female wistar- kyoto (WKY) and spontaneously hypertensive ... Myelinated fibers and axons distribution in phrenic nerve of male and female wistar- kyoto (WKY) and spontaneously hypertensive ... with special attention to myelinated fiber and their respective axons area and diameter. Our results showed for male and female ... of the diaphragm showed gender differences in fiber composition but gender differences on phrenic nerve myelinated fiber ...
... that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system. The ... axons are myelinated by oligodendrocytes, thus lack neurolemma. The myelin sheaths of Oligodendrocytes do not have neurolemma ... Neurolemma serves a protective function for peripheral nerve fibers. Damaged nerve fibers may regenerate if the perikaryon is ... The neurolemma forms a regeneration tube through which the growing axon reestablishes its original connection. A neurilemoma is ...
... axons in specific white matter pathways. The corpus callosum (CC), a major white matter structure interconnecting brain ... Advances in brain connectomics set the need for detailed knowledge of functional properties of myelinated and non-myelinated ( ... Nerve Fibers, Myelinated / physiology* * Nerve Fibers, Unmyelinated / pathology* * Optic Nerve / physiology * Optic Nerve / ... the optic nerve where all axons are myelinated, the CC contains also a large population of non-myelinated axons, making it ...
... that chitin conduit combined with exosomes from GMSCs could significantly increase the number and diameter of nerve fibers and ... The exosomes from GMSCs could significantly promote Schwann cell proliferation and DRG axon growth. The in vivo studies showed ... The effects of exosomes on peripheral nerve regeneration in vitro were evaluated by coculture with Schwann cells and DRGs. The ... Histology, electrophysiology, and gait analysis were used to test the effects of exosomes on sciatic nerve function recovery in ...
Both the peripheral process and the axon are myelinated. In humans, there are on average 30,000 nerve fibers within the ... has an average of 50,000 fibers. The peripheral axons of auditory nerve fibers form synaptic connections with the hair cells of ... Each type I axon innervates only a single inner hair cell, but each inner hair cell is innervated by up to 30 such nerve fibers ... The cochlear nerve (also auditory or acoustic neuron) is one of two parts of the vestibulocochlear nerve, a cranial nerve ...
Unmyelinated fibers and myelinated axons of the mammalian central nervous system do not regenerate. ... However, the myelin layer does not ensure a perfect regeneration of the nerve fiber. Some regenerated nerve fibers do not find ... non-myelinated axons (or intermittently myelinated axons, meaning axons with long non-myelinated regions between myelinated ... are passed along the axon.[1] The myelinated axon can be likened to an electrical wire (the axon) with insulating material ( ...
Unmyelinated fibers and myelinated axons of the mammalian central nervous system do not regenerate. Some studies have revealed ... However, the myelin layer does not ensure a perfect regeneration of the nerve fiber. Some regenerated nerve fibers do not find ... Myelinated axons are white; hence, the "white matter" of the brain. Myelin insulates axons from electrically charged atoms and ... Along unmyelinated fibers, impulses continuously move as waves, but, in myelinated fibers, they "hop" or propagate by saltatory ...
Alzheimer Disease; Astrocytes; Axons; Blood-Brain Barrier; Capillaries; Cerebrovascular Circulation; Microscopy; Nerve Fibers, ... Schain AJ, Hill RA, Grutzendler J: Label-free in vivo imaging of myelinated axons in health and disease with spectral confocal ... Label-free in vivo imaging of myelinated axons in health and disease with spectral confocal reflectance microscopy. Label-free ... AXONAL AND SYNAPTIC DEGENERATION/REGENERATION: We have recently developed a method for imaging myelinated axons in vivo ( ...
In the present study, a 10 mm long gap in the median nerve was repaired with 12 mm SilkBridgeTM conduit and evaluated at middle ... In the present study, a 10 mm long gap in the median nerve was repaired with 12 mm SilkBridge conduit and evaluated at middle ... conduit led to a very good functional and morphological recovery of the median nerve, similar to that observed with the ... The SilkBridgeTM conduit led to a very good functional and morphological recovery of the median nerve, similar to that observed ...
These include cutaneous and subcutaneous fibers, somesthetic and proprioceptive fibers, and motor ax... more ... The SEP stimulus preferentially excites only the largest myelinated fibers in the peripheral nerve. ... The SEP stimulus preferentially excites only the largest myelinated fibers in the peripheral nerve. These include cutaneous and ... potential that travels up the axon toward the spinal cord and past the cell bodies of the sensory axons of the large-fiber ...
Number of myelinated axons, myelinated fiber diameter, myelin thickness, fiber distributions, myelinated fiber density, and ... Axons, rather than full fiber circumference, are used to identify distinct nerve fibers and overcome the problem of myelin ... Myelin is thus counted only if its axon is in the region of interest. B. Final Image for Analysis after automatic fiber debris ... D. Image use to analyze axon features. E. Image used to measure fiber features by combining bitplanes from image C and D ...
... star labels the axon with a normal myelin sheath). (I) Amount of myelin outfoldings in myelinated fibers in optic nerves ... A, B) Longitudinal and cross sections of P10 optic nerve myelinated axons showing cytoplasmic channels within the compact ... Amount of myelinated axons with non-compacted layers in wild-type and shiverer heterozygote (Shiv +/-) optic nerves between P10 ... E) Amount of myelinated axons with non-compacted layers in wild-type, Shiv +/-, CNP +/- and CNP -/- at P10. Bars show mean ± SD ...
... in the formation of functional distinct domains critical for saltatory conduction of nerve impulses in myelinated nerve fibers ... This protein is localized at the juxtaparanodes of myelinated axons, and mediates interactions between neurons and glia during ... Required, with CNTNAP1, for radial and longitudinal organization of myelinated axons. Plays a role ... nervous system development and is also involved in localization of potassium channels within differentiating axons. This gene ...
Axons (1). * Immunoprecipitation (1). * Myelinated nerve fibers (1). * Nerve fibers (1). * Nerves (1) ... Schwann cells ER-associated degradation contributes to myelin maintenance in adult nerves and limits demyelination in CMT1B ... an abundant component of peripheral nerve myelin. In humans, mutations in P0 cause the demyelinating Charcot-Marie-Tooth 1B ( ...
The muscle fibers showed no intrinsic abnormalities. Biopsy of the sural nerve showed scattered axons with very thin myelin ... There was also a nearly complete loss of large diameter myelinated fibers. No onion bulb formations were noted. These findings ... Nerve conduction study showed absence of motor and sensory action potentials in the hands when the nerves in the upper limbs ... A biopsy of the quadriceps muscle showed mild variability in fiber diameter, but no group typing or group atrophy. ...
The muscle fibers showed no intrinsic abnormalities. Biopsy of the sural nerve showed scattered axons with very thin myelin ... There was also a nearly complete loss of large diameter myelinated fibers. No onion bulb formations were noted. These findings ... Nerve conduction study showed absence of motor and sensory action potentials in the hands when the nerves in the upper limbs ... It is widely held that a glutamate-like toxin that resembles N-methyl-D-aspartate may be responsible for the death of nerve ...
Click here for Axon of nerve cells pictures! You can also find pictures of Bone marrow, Biceps brachii muscle, Biceps brachii, ... Myelinated Axon loss: Severe ¸æ¼ÁÌä¤Ï ¤³¤Á¤é ¤Þ¤Ç¤ª´ê¤¤¤·¤Þ¤¹¡£ LS Myelinated Nerve Fibers Image No. 3583503 Model Release * ... The whiter outer area of the butterfly shape is made up of myelinated axons. Axons are the parts of... Add to Cart Download ... More information about the different primary afferent axons: A-alpha nerve fibers carry information... Because the technique ...
... mucosa identified frequent focal degeneration of myelinated nerve fibers and axons. Degenerative changes in peripheral nerves, ... The afferent nerve fibers via above-mentioned cranial nerves project from the pharynx and tongue to the NTS, and synapse with ... With aging, in addition to sensory decline [46], there are changes in motor nerve axon, including axonal flow, axon terminals, ... 5. Mutability of Muscle Fiber Types: Loss of Aerobic Tonic Type I Muscle Fibers in Upper Airway Dilator Muscles in OSA. The ...
2012). Enriched environment increases the myelinated nerve fibers of aged rat corpus callosum. Anat. Rec. 295, 999-1005. doi: ... myelinated fiber and sheath volume, and myelinated fiber length, particularly of smaller axons that were less than 1 μm wide ( ... Tasaki, I. (1939). The electro-saltatory transmission of the nerve impulse and the effect of narcosis upon the nerve fiber. Am ... thinner myelin and fewer myelinated axons in the optic nerve from P18 to P21 although this difference was no longer seen at P70 ...
Retinal axons in the retinal nerve fiber layer (RNFL) are non-myelinated until they penetrate the lamina cribrosa. Hence, the ... readers will given insights into effects on the retina and the and optic nerve. Individual chapters are also devoted to OCT ...
myelinated fiber structure one axon, many schwann cells. intervals w nodes of ranvier ... nerve fibre (nerve). microtubules make up its skeleton. many mitochondria bc its metabolically active. gets rid of material ... axon (microtubules, neurofillaments, trunk)= output = efferent. cell bodies in nervous tissue. soma = body. cytoplasm = ...
... the lipid substance forming a sheath around the axons of certain nerve fibers; these nerve fibers are spoken of as myelinated ... which are called myelinated or medullated fibers. adj., adj myelin´ic. Myelinated nerve fibers occur predominantly in the ... Myelinated nerve fibers occur predominantly in the cranial and spinal nerves and compose the white matter of the brain and ... around the axons of certain nerve fibers; it is an electrical insulator that serves to speed the conduction of nerve impulses ...
... or axons, make up the nervous system. The axons are grouped together in nerve... ... Anatomy of a Nerve More than ten thousand million nerve cells and their fibers, ... They are called myelinated nerve fibers. The myelinated sheath has regular indentations along its length called the nodes of ... Anatomy of a Nerve. More than ten thousand million nerve cells and their fibers, or axons, make up the nervous system. The ...
What is ampullar nerve, inferior? Meaning of ampullar nerve, inferior medical term. What does ampullar nerve, inferior mean? ... Looking for online definition of ampullar nerve, inferior in the Medical Dictionary? ampullar nerve, inferior explanation free ... nerve fiber,. n a slender process of a neuron, usually the axon. Each fiber is classified as myelinated or unmyelinated. ... medullated nerve myelinated nerve.. mixed nerve (nerve of mixed fibers) a nerve composed of both sensory (afferent) and motor ( ...
  • Neuroglia called oligodendrocytes form an insulating coat or myelin sheath that wraps around neuronal axons. (thoughtco.com)
  • Advances in understanding the molecular neurobiology of myelinated axons, as described in Chapter 2 , have revealed much about the contribution of impaired impulse conduction to symptom production in MS. Nonetheless, there is much more to learn about the mechanisms underlying demyelination and axonal injury in MS. What are the precise molecular steps that lead from the initial immunologic assault to the death of oligodendrocytes and the degeneration of axons? (nap.edu)
  • The rapid conduction velocity and successful transmission of electric signals in mammalian myelinated axons depend on the proper spatial distribution of voltage-gated ion-selective channels. (jneurosci.org)
  • This reduction in axonal caliber in the proximal stumps is associated with a selective diminution in the amount of NF protein undergoing slow axonal transport in these axons, with a decrease in axonal NF content, and with reduced conduction velocity. (pnas.org)
  • This patient had a motor median nerve conduction velocity of 8 m/s. (neurology.org)
  • At a synapse, the membrane of the axon closely adjoins the membrane of the target cell, and special molecular structures serve to transmit electrical or electrochemical signals across the gap. (wikipedia.org)
  • Conglomerates of gray matter that are located below the cortex include the basal ganglia , cranial nerve nuclei, and midbrain structures such as the red nucleus and substantia nigra. (thoughtco.com)
  • One can tweak the parameters to let the axon spike normally but I wonder if there is a physiologically plausible model for thin myelinated axons out there I am not aware of. (yale.edu)
  • Advances in brain connectomics set the need for detailed knowledge of functional properties of myelinated and non-myelinated (if present) axons in specific white matter pathways. (nih.gov)
  • Although autologous nerve transplantation remains the preferred strategy for reconstruction, it is limited by donor tissues, the sacrifice of functional nerves, and the potential formation of neuromas [ 4 - 6 ]. (hindawi.com)
  • The SilkBridge TM conduit led to a very good functional and morphological recovery of the median nerve, similar to that observed with the reference autograft nerve reconstruction procedure. (frontiersin.org)
  • The newly regenerated nerve fibers were functional and myelinated. (wingsforlife.com)
  • Nerve injuries that include complete transection of the nerve results in degeneration occurs both distal to the lesion segment by Wallerian degeneration and proximal to the lesion segment by retrograde degeneration [ 17 ], which lead to motor and sensory functional damage at the spot of the lesion. (springer.com)
  • Treatments with GSK-3 inhibitors including a clinical dose of lithium to rats with thoracic spinal cord transection or contusion injuries induce significant descending corticospinal and serotonergic axon sprouting in caudal spinal cord and promote locomotor functional recovery. (rutgers.edu)
  • Finally, they found increases in the diameters of some of the largest axons among only this group and they speculate that together, these changes may alter functional coupling between the cingulate cortex and subcortical structures such as the amygdala and nucleus accumbens (areas of the brain linked respectively to emotional regulation and to reward and satisfaction) and contribute to altered emotional processing in people who have been abused during childhood. (innerself.com)
  • The first highly-descriptive, successful neuron model was designed from a squid axon (The Hodgkin Huxley model) because they have giant axons that those old electric probes could actually take meaningful measurements from. (physicsforums.com)
  • Certainly, a squid axon is going to be much bigger than any human axon. (physicsforums.com)
  • N. H. Sabah and K. N. Leibovic, Subthreshold oscillatory responses of the Hodgkin-Huxley cable model for the giant squid axon , Biophys. (ams.org)
  • FitzHugh R. and Cole K.S. (1964) Theoretical potassium loss from squid axons as a function of temperature. (scholarpedia.org)
  • AFAIK there is no "standard model" for myelinated axons--at least, nothing with the stature of the HH squid axon model. (yale.edu)
  • Thus, fiber degeneration, which was probably secondary to impaired axonal transport, could indicate that myelinated axons require local oligodendroglial support. (nih.gov)
  • Crucial to the trophic relations within the axon, axonal transport serves as a mode of intracellular communication carrying molecules and information along microtubules and intermediate filaments from the neuronal cell body to the axon terminal (anterograde transport) or from the axon terminal to the neuronal cell body (retrograde transport). (nysora.com)
  • The nerve endings show enlarged "boutons terminaux" and a widespread enlargement of nerve terminals from the accumulation of neurofilaments. (nih.gov)
  • 1 These pathologic changes cause ectopic discharge or impulse generation from sites along axons where damage has occurred, rather than just at sensory nerve endings. (asahq.org)
  • The cornea is innervated by a densely arranged network of fine nerve endings that are located primarily in the epithelial layer and are supplied by the long ciliary nerves, derived from the trigeminal nerve (cranial nerve V). The long ciliary nerves produce a circular limbal plexus in the eye, from which 70 to 80 nerve trunks enter the corneal stroma, to a depth of 150 μm. (arvojournals.org)
  • 1 . McIntyre CC, Richardson AG, Grill WM (2002) Modeling the excitability of mammalian nerve fibers: influence of afterpotentials on the recovery cycle. (yale.edu)
  • Modeling the excitability of mammalian nerve fibers: influence of afterpotentials on the recovery cycle. (yale.edu)
  • The cochlear nerve (also auditory or acoustic neuron ) is one of two parts of the vestibulocochlear nerve , a cranial nerve present in amniotes , the other part being the vestibular nerve. (wikipedia.org)
  • Symptoms of nerve injury include paresthesias, loss of sensation and position sense, impaired motor function, cranial nerve malfunction, changes in reflexes, and impairments in glandular secretion. (tabers.com)
  • cranial nerve for illus. (tabers.com)
  • The components of the eighth cranial nerve (CN VIII) carrying axons that convey information regarding sound and balance between the spiral ganglion in the inner ear and the cochlear nuclei in the brainstem. (tabers.com)
  • Uncommonly, cranial nerve involvement will produce prominent bulbar insufficiency with consequent airway compromise, and intubation may be necessary to protect the airway before ventilation is critically diminished due to muscle weakness. (clinicaladvisor.com)