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AN ELECTRON MICROSCOPE STUDY OF THE PERIPHERAL NERVES OF THE HAGFISH ( MYXINE GLUTINOSA , L.)
Author(s) -
Peters A.
Publication year - 1964
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1964.sp001702
Subject(s) - axolemma , endoneurium , hagfish , anatomy , axon , schwann cell , electron microscope , basement membrane , biology , peripheral nerve , physics , myelin , neuroscience , central nervous system , optics , biochemistry , gene , vertebrate
The peripheral nerves of the hagfish, Myxine glutinosa , L. have been studied by electron microscopy. These nerves are unmyelinated and each axon is separately enclosed by a sheath composed of single layer of Schwann cells, whose nuclei lie parallel to the long axis of the nerve. Usually each axon has its own individual sheath, but sometimes two axons, though separated, are ensheathed by the same Schwann cell. In transverse sections, the number of cells forming the sheath varies with the diameter of the axon; fibres of diameter 3 µ and less, have sheaths composed of a single Schwann cell, but a number of cells are present in the sheaths of the larger axons. Where adjacent Schwann cells come together, they are most commonly separated by a distance of about 120 Å, and this is the distance that separates the irregular inner surface of the Schwann cell sheath from the axolemma. The outer surface of each sheath is smooth and is separated from the collagen and reticulin of the endoneurium by a basement membrane.