Found 2 items, similar to Medullary sheath.
English → English (WordNet)
Definition: medullary sheath
medullary sheath
n : a layer of myelin encasing (and insulating) the axons of
medullated nerve fibers [syn:
myelin sheath]
English → English (gcide)
Definition: Medullary sheath
Sheath
\Sheath\, n. [OE. schethe, AS. sc[=ae][eth],
sce['a][eth], sc[=e][eth]; akin to OS. sk[=e][eth]ia, D.
scheede, G. scheide, OHG. sceida, Sw. skida, Dan. skede,
Icel. skei[eth]ir, pl., and to E. shed, v.t., originally
meaning, to separate, to part. See
Shed.]
1. A case for the reception of a sword, hunting knife, or
other long and slender instrument; a scabbard.
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The dead knight's sword out of his sheath he drew.
--Spenser.
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2. Any sheathlike covering, organ, or part. Specifically:
(a) (Bot.) The base of a leaf when sheathing or investing
a stem or branch, as in grasses.
(b) (Zo["o]l.) One of the elytra of an insect.
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Medullary sheath. (Anat.) See under
Medullary.
Primitive sheath. (Anat.) See
Neurilemma.
Sheath knife, a knife with a fixed blade, carried in a
sheath.
Sheath of Schwann. (Anat.) See
Schwann's sheath.
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Medullary
\Med"ul*la*ry\, a. [L. medullaris, fr. medulla marrow:
cf. F. m['e]dullaire.]
1. (Anat.)
(a) Pertaining to, consisting of, or resembling, marrow or
medulla.
(b) Pertaining to the medula oblongata.
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2. (Bot.) Filled with spongy pith; pithy.
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Medullary groove (Anat.), a groove, in the epiblast of the
vertebrate blastoderm, the edges of which unite, making a
tube (the medullary canal) from which the brain and spinal
cord are developed.
Medullary rays (Bot.), the rays of cellular tissue seen in
a transverse section of exogenous wood, which pass from
the pith to the bark.
Medullary sheath (Anat.), the layer of white semifluid
substance (myelin), between the primitive sheath and axis
cylinder of a medullated nerve fiber.
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