Myelin Wallerian degeneration

Wallerian degeneration is the secondary disruption of the myelin sheath and axon distal to the injury 518... 

FIGURE BO-2 Wallerian degeneration in the PNS. After an axon is injured, resulting chromatolysis, i.e. stress reaction and increased protein synthesis, occurs in the neuronal cell body, with axonal and myelin degeneration distal to the injury. Growth-permissive Schwann cells secrete growth factors that stimulate axons to regenerate. 

Stoll, G., Griffin, J. W., Li, C. Y. and Trapp, B. D. Wallerian degeneration in the peripheral nervous system participation of both Schwann cells and macrophages in myelin degradation./. Neurocytol. 18 671-683,1989. 

Griffin JW, George R, Lobato C, Tyor WR, Yan LC, Glass ID (1992) Macrophage responses and myelin clear ance dining Wallerian degeneration Relevance to immune-mediated demyelination. J Neuroimminiol 40 153—165. 

Buss A, Pech K, Merkler D, Kakulas BA, Martin D, Schoenen J, Noth J, Schwab ME, Brook GA (2005) Sequential loss of myelin proteins during Wallerian degeneration in the human spinal cord. Brain 128 356-364. 

Stoll G, Trapp BD, Griffin JW (1989) Macrophage function during Wallerian degeneration of rat optic nerve Clearance of degenerating myelin and la expression. 1 Neurosci 9 2327-2335. 

Sheikh, K A, Sun, J, Liu, Y, Kawai, H, Crawford, T O, Proia, R L, Griffin, J W, Schnaar, R L, Mice lacking complex gangliosides develop Wallerian degeneration and myelination defects, Proc. Natl. Acad. Set USA, 96, 7532-7537, 1999. 

Liu, K. M. and Shen, C. L., Ultrastructural sequence of myelin breakdown during Wallerian degeneration in the rat optic nerve, Cell Tissue Res., 242, 245, 1985. 

Events surrounding Wallerian degeneration in the nerve are well described (Lampert, 1967 Sal-zer and Bunge, 1980 Lubinska, 1982). Schwann cells proliferate in the basement membrane tubes of the formerly myelinated nerve fibers (Asbury and Johnson, 1978). Premitotic incorporation of thymidine in Schwann cells spreads proximo-... 

Lubinska, L. (1982) Patterns of Wallerian degeneration of myelinated fibers in short and long peripheral stumps and in isolated segments of rat phrenic nerve. Interpretation of the role of axoplasmic flow of the trophic factor. Brain Res. 233 227-240. 

Lead-exposed nerves have often been reported to show evidence of damage in their axonal fibres as well as in myelin sheaths. Schlaepfer (1969) has shown this phenomenon. He exposed adult rats massively to lead (2.4-3.0g lead acetate/kg/day for between 3 and 18 months). Characteristic myelin sheath changes were noted in hindlimb nerves, while Wallerian degeneration,... 

With the electronmicroscope the axoplasm may appear coarsely granulated and peripherally displaced. In the presence of structurally intact myelin this is strongly reminiscent of very early Wallerian degeneration ( Vial 1958, Terry and Harkin 1959, Terry and Weiss 1963). 

Histological examination of hens exposed to TOCP revealed a wallerian dying-back degeneration of the larger diameter axons and myelin sheaths. If the neuropathic target esterase is inhibited by 70%, the typical organophophorus ester-induced delayed neurotoxicity (OPIDN) will follow after an approximate 7-14 day delay. 

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