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SCHWANN CELL RESPONSES DURING REGENERATION AFTER ONE OR MORE CRUSH INJURIES TO MYELINATED NERVE FIBRES
Author(s) -
OHARA SHINJI,
IKUTA FUSAHIRO
Publication year - 1988
Publication title -
neuropathology and applied neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.538
H-Index - 95
eISSN - 1365-2990
pISSN - 0305-1846
DOI - 10.1111/j.1365-2990.1988.tb00884.x
Subject(s) - axon , schwann cell , regeneration (biology) , anatomy , crush injury , wallerian degeneration , basal lamina , supernumerary , biology , population , myelin , cytoplasm , neuroscience , microbiology and biotechnology , medicine , ultrastructure , central nervous system , surgery , environmental health
Schwann cell responses during regeneration after one or more crush injuries to myelinated nerve fibres The responses of Schwann cells during regeneration of myelinated nerve fibres were studied ultrastructurally in the distal segment of mouse phrenic nerve after a single or repeated localized crush injury. Chronological observations on nerves after a single crush confirmed the occurrence of myelination of only single regenerating axons among many that appeared in individual Bungner bands. The redundant axon sprouts often showed the structural features of degeneration and decreased in number with time. During the process, supernumerary Schwann cells not related to myelin formation were produced. They commonly failed not only to make a one–to–one relationship with an axon, but they also failed to acquire a new basal lamina of their own. With time, they showed shrinkage of their cytoplasm and became arranged circumferentially around the myelinating axon with unipolar or bipolar cytoplasmic processes. Electron microscopic, quantitative assessment of the nuclear population of Schwann cells following repeated crushes up to four times, clearly indicated a progressive and predominant increase in the number of the supernumerary Schwann cells with the number of crushes. Also, they were found to form separate concentric cytoplasmic lamellae around the myelinating axons, developing structures resembling onion–bulbs. It was concluded that essentially the same regenerating process as that observed after a single crush was repeated following re–crush, thereby resulting in the successive accumulation of supernumerary Schwann cells around a myelinating axon.