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Myelin Sheath definition: The lipid-rich sheath surrounding AXONS in both the central and peripheral nervous systems. 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.
myelin sheath definition: An electrically insulating fatty layer that surrounds the axons of many neurons. It is an outgrowth of glial cells: Schwann cells supply the myelin for peripheral neurons while oligodendrocytes supply it to those of the central nervous system. [GOC:jl, Wikipedia:Myelin]
myelin definition: (MYE-eh-lin) The fatty substance that covers and protects nerves.
Myelin Sheath definition: A layer of phospholipids and protein found on neuronal axons. This structure acts as an electrical insulator that allows nerve impulses to travel faster by increasing the resistance and decreasing the capacitance over that found in unmyelinated nerve fibers.
Catheters, Urinary, External, Drainage definition: External urinary catheters designed to drain urine from outside the body instead of within the bladder (i.e., external use) in males. These catheters consist of a plastic condom ending in an open tube that is attached to a drainage bag through a connecting tube. The diameter of the condom is chosen to match the diameter of the penis; they may be self-adhesive or attached by pressure. External-drainage urinary catheters are mostly used for urinary incontinence management in patients who can void spontaneously but do not retain urine.
SHEATH, FOR ENDOSCOPE definition: An endoscope and accessories is a device used to provide access, illumination, and allow observation or manipulation of body cavities, hollow organs, and canals. The device consists of various rigid or flexible instruments that are inserted into body spaces and may include an optical system for conveying an image to the user's eye and their accessories may assist in gaining access or increase the versatility and augment the capabilities of the devices. Examples of devices that are within this generic type of device include cleaning accessories for endoscopes, photographic accessories for endoscopes, nonpowered anoscopes, binolcular attachments for endoscopes, pocket battery boxes, flexible or rigid choledochoscopes, colonoscopes, diagnostic cystoscopes, cystourethroscopes, enteroscopes, esophagogastroduodenoscopes, rigid esophagoscopes, fiberoptic illuminators for endoscopes, incandescent endoscope lamps, biliary pancreatoscopes, proctoscopes, resectoscopes, nephroscopes, sigmoidoscopes, ureteroscopes, urethroscopes, endomagnetic retrievers, cytology brushes for endoscopes, and lubricating jelly for transurethral surgical instruments. This section does not apply to endoscopes that have specialized uses in other medical specialty areas and that are covered by classification regulations in other parts of the device classification regulations.
Endoscope Sheaths definition: Single-use sheaths designed as the outer component of a two-part flexible endoscope. These sheaths cover and protect all working surfaces of the endoscope from contamination; they may include air, water, and suction/biopsy channels as integral parts. The reusable part of the endoscope contains the fiber optics and control devices appropriate for the intended use (e.g., colonoscope, gastroscope, sigmoidoscope). Those sheaths not including channels may be used as a disposable cover for most models of nasopharyngolaryngoscopes. Endoscope sheaths are disposed of after one use, minimizing the need for cleaning and eliminating disinfection during endoscopic reprocessing between procedures.
Nerve Tissue and Nerve Sheaths definition: Tissues that contain neurons and supporting cells that form the covers encircling nerves, nerve fibers, and axons.
Nerve Tissue, Neuroepithelial Tissue, and Nerve Sheaths definition: The basic components of the nervous system. They contain neurons, supporting cells, and neuroepithelial cells.

Identification of Maize Silicon Influx Transporters: ... more in the leaf sheaths and blades. Different ...

Namiki Mitani et al.

Plant and Cell Physiology , 01 Jan 2009

Trace metal concentrations in Posidonia oceanica of North Corsica (northwestern Mediterranean Sea): use as a biological monitor?: ... As, Se, Cd, and Pb) in sheaths dated by ...

Marc Gosselin et al.

BMC Ecology , 11 Sep 2006

Gene-expression profile comparisons distinguish seven organs of maize: ... (leaf blades, leaf sheaths and roots), husk leaves ...

Yangrae Cho et al.

Genome Biology , 2002

Purinergic receptors are part of a signalling system for proliferation and differentiation in distinct cell lineages in human anagen hair follicles: ... inner and outer root sheaths and medulla and P2Y 2 ...

Aina V. H. Greig et al.

Purinergic Signalling , 01 Dec 2008

Pain as a symptom of peripheral nerve sheath tumors: clinical significance and future therapeutic directions: ... of peripheral nerve sheaths are relatively uncommon ...

Michael E Sughrue et al.

Journal of Brachial Plexus and Peripheral Nerve Injury , 29 Feb 2008

Switching myelination on and off: ... stably maintain myelin sheaths around axons and also ...

James L. Salzer

The Journal of Cell Biology , 19 May 2008

Endoscopically Based Endonasal and Transnasal Lasersurgery: ... designed applicator sheaths, which incorporate the ...

Hans Scherer et al.

Diagnostic and Therapeutic Endoscopy , 2001

Blood-brain barrier dysfunction in acute lead encephalopathy: a reappraisal.: ... or perivascular glial sheaths. Furthermore, no ...

T W Bouldin et al.

Environmental Health Perspectives , 01 Dec 1975

Distal axonopathy: one common type of neurotoxic lesion.: ... (neuronopathy), myelin sheaths (myelinopathy) and ...

P S Spencer et al.

Environmental Health Perspectives , 01 Oct 1978

Sheathing of the Endovaginal Ultrasound Probe: Is It Adequate?: ... ultrasonographer. The sheaths were then tested for ...

Ronald Jimenez et al.

Infectious Diseases in Obstetrics and Gynecology , 1993

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