neurilemma Anat.
(njʊərɪˈlɛmə)
Also neurilema (njʊəraɪˈliːmə), -elema; (sense c) neurolemma.
[Orig. f. Gr. νεῦρ-ον nerve + εἴληµα covering, involucrum; subsequently taken as f. Gr. λέµµα husk, skin (correctly reformed neurolemma). Cf. F. névrilème (Bichat, 1801).]
a. The delicate membranous outer sheath which invests and protects a nerve (now usually called epineurium). b. The sheath of a nerve-funiculus, the perineurium.
Senses a, b are now rare or Obs.
| α 1830 R. Knox Béclard's Anat. 357 These filaments, as they penetrate into the ganglia, leave off their neurilema. 1846 F. Brittan tr. Malgaigne's Man. Oper. Surg. 285 The optic nerve, with the neurelema of which it appears to become continuous. 1856–8 W. Clark Van der Hoeven's Zool. I. 11 The nerve-stems and the bundles of which they consist, are surrounded with coats of conjunctive tissue, called neurilema. |
| β 1825 Good Study Med. (ed. 2) IV. 24 Solid fibres or capillaments of a particular kind, the neurilemma of Bichat. 1851 Carpenter Man. Phys. (ed. 2) 224 When the neurilemma has been removed, and the trunk has been separated into its component fasciculi. 1888 Rolleston & Jackson Anim. Life 212 The giant fibres are separated from the nerve-cord by the inner neurilemma. |
| attrib. 1889 Allbutt's Syst. Med. VI. 626 If the nucleus of the segmental neurilemma cell remain perfectly healthy. Ibid. 643 Leucocytes enter the neurilemma sheath. |
c. The thin outer sheath that is seen with the light microscope surrounding the axon (and the myelin sheath, if present) of an individual peripheral nerve fibre; also called
sheath of Schwann. (The usual sense.)
| 1852 Dana Crust. ii. 1333 The nerves..are flat, fibrous cords, enclosed within a membranous envelope or neurolemma. 1874 A. E. J. Barker tr. Frey's Histol. & Histochem. of Man 307 The existence of an envelope on the nervous tube [sc. fibre] is easily inferred... This neurilemma may be seen not infrequently as [etc.]. Ibid. 317 The nerves of the brain and spinal cord..become clothed with a delicate envelope at their exit from the nervous centres. This covering receives another addition from the dura mater of connective-tissue bundles in its passage through the latter, and..constitutes what was formerly known as ‘neurilemma’, but which we will designate from henceforth ‘perineurium’. 1890 Gray's Anat. (ed. 12) 42 The tubular sheath of the funiculi, called the neurilemma or perineurium. 1892 E. A. Schäfer Essent. Histol. (ed. 3) xviii. 83 Outside the medullary sheath is a delicate but tough homogeneous membrane, the primitive sheath or nucleated sheath of Schwann... The primitive sheath is also known as the neurolemma. 1930 Maximow & Bloom Text-bk. Histol. xii. 251 Some European writers, like Cajal, apply the term ‘neurilemma’ to the epineurium and not to the sheath of Schwann of the individual fibers. 1966 Wright & Symmers Systemic Path. II. xxxiv. 1252/1 Neurolemmomas arise from the cells of the neurolemma, or nerve sheath. It is believed that the cell of origin is the Schwann cell. 1968 Bloom & Fawcett Textbk. Histol. (ed. 9) xii. 321/1 The myelin is actually part of the Schwann cell, consisting of spirally wrapped layers of its surface membrane... The outer membrane..and the protein-polysaccharide boundary layer on its outer aspect were resolved with the light microscope as a single layer, which has traditionally been called the neurilemma. |
Hence
neuriˈlemmal a. (now the usual
adj.); also
neurileˈm(m)atic a. [F.
névrilématique];
neuriˈlem(m)atous a.| 1836–9 Todd's Cycl. Anat. II. 534/2 The expansion and interlacing of the neurilemmatic sheaths. 1839–47 Ibid. III. 776/1 The plaiting must be considered..independent of neurilematous investment. 1875 Payne Jones & Siev. Path. Anat. 310 The neurilemmatous sheath is the part mainly affected in inflammation. 1903 Rep. Brit. Assoc. Adv. Sci. 1902 782 From the microscopic study of the distal portions of divided nerve⁓trunks we arrived at the conclusion that the activity of the neurilemmal cells has some relation to the development of the new nerve-fibres. 1937 E. E. Hewer Text-bk. Histol. 96 Within the central nervous system there is no neurilemmal sheath. 1954 T. L. Peele Neuroanat. Basis Clin. Neurol. i. 13/2 The neurolemmal sheath of the spinal nerves, and of those cranial nerves possessing it, terminates (or begins) a short distance from spinal cord or brain stem. 1973 H. M. Ráliš et al. Techniques Neurohistol. i. 19 The neurilemmal sheath plays an important role in the nutrition and protection of nerve fibres. |