▪ I. myelin1, -ine
(ˈmaɪəlɪn)
[a. G. myelin, f. Gr. µνελός marrow: see -in, -ine.]
1. Chem. Virchow's term for a fatty substance obtainable from various animal tissues (e.g. brain-substance, yolk of egg), and also from some vegetable tissues. Also attrib.
| 1867 Syd. Soc. Bienn. Retrosp. 11 The peculiar substance termed by Virchow, myeline substance..appears to be derivable from protagon. 1867 Jrnl. Anat. I. 359 So-called Myeline-forms (rounded and elongated bodies with double contours, resembling nerve-tubes). 1887 tr. De Bary's Fungi, etc. 300 The motile formations observed in Beneke's myelin (protagon-mixtures). |
2. Anat. The medullary sheath of nerve-fibres, or white substance of Schwann. Also
attrib.| 1873 A. Flint Physiol. Man, Nervous Syst. i. 21 The medullary substance..is called by various names; as myeline, white substance of Schwann, medullary sheath. 1896 Allbutt's Syst. Med. I. 176 The nerve fibres..undergo changes in the myelin sheath similar to degeneration. |
Hence
ˈmyelinate,
ˈmyelinated adjs., (of nerve-fibres) furnished with myelin;
myeliˈnation, the process of development of the medullary sheath of nerves in the embryo (
Syd. Soc. Lex. 1891);
myeˈlinic a., of or containing myelin;
myeliniˈzation = myelination;
ˈmyelinize v. trans., to furnish with myelin;
ˌmyelino-neuˈritis, inflammation of the medullary sheath of nerves.
| 1894 Lancet 3 Nov. 1037/1 In a muscular nerve trunk from one-third to one-half of the *myelinate fibres are from cells of the spinal root ganglion. |
| 1899 Allbutt's Syst. Med. VII. 75 An exceedingly small group of *myelinated fibres. |
| Ibid. 732 The changes in the cortex begin at a stage prior to the *myelination of the pyramidal fibres. |
| 1900 Lancet 18 Aug. 529 The order of succession in the *myelinisation of the projection centres and the association centres. |
| 1903 Contemp. Rev. Sept. 389 When the child plays it is literally organising its brain, *myelinising its mind-machine. |
| 1876 tr. Wagner's Gen. Pathol. 329 Neither protagon..nor one of its products of decomposition..arising from the action of alkalies furnish of themselves *myelinic forms. |
| 1897 Allbutt's Syst. Med. II. 979 *Myelino-neuritis such as is met with in disseminated sclerosis. |
▪ II. myelin2 Min. (
ˈmaɪəlɪn)
Also
-ine.
[a. G. myelin (Breithaupt), ad. Gr. µυέλινος marrowy, f. µυελ-ός marrow.] A yellowish- or reddish-white variety of kaolin; so called from its appearance.
| 1854 Dana Min. 250 Myelin of Breithaupt (Talksteinmark) is from Rochlitz. |