medullary sheath
Americannoun
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Botany. a narrow zone made up of the innermost layer of woody tissue immediately surrounding the pith in plants.
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Anatomy. myelin sheath.
noun
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anatomy a myelin layer surrounding and insulating certain nerve fibres
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a layer of thick-walled cells surrounding the pith of the stems of some higher plants
Etymology
Origin of medullary sheath
First recorded in 1840–50
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Related to this substance are ``neuro-keratin,'' found in the medullary sheath of nerves, and ``gorgonin,'' the matrix of the axial skeleton of the coral Gorgonia Cavolinii.
From The Project Gutenberg Encyclopedia Volume 1 of 28 by Project Gutenberg
The investment of nerve fibers with a protective covering or medullary sheath, consisting of white, fat-like matter.
From Youth: Its Education, Regimen, and Hygiene by G. Stanley Hall
MS, medullary sheath, the dark, irregular ring just inside the bundles.
From Wood and Forest by William Noyes
It will help in understanding the peripheral system to remember that a nerve consists of a bundle of neurone fibers each wrapped in its medullary sheath and sheath of Schwann.
From The Mind and Its Education by George Herbert Betts
The medullary sheath may also aid in the nourishment of the axis cylinder.
From Physiology and Hygiene for Secondary Schools by Francis M. Walters
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