The Ist change occurring in a sharp cut nerve is:
B i.e. Degeneration of myelin sheath Changes in Nerve Fiber after Injury Degeneration of the distal pa (Antegrade) Degeneration of proximal pa (Retrograde) Stage of Regeneration * Degeneration of distal pa (distal to cut) is called * Same as distal generation hut * Axis cylinder:, from :,tiiiiip. Wallerian degeneration.Q upto nearest node of ranvier grows & sprout out (pseudopod * Within 24 hours histological and chemical changes occur (nearest collateral)Q like structure of fibril) * The axon cylinder swells up & breaks down into small * Changes in the cell body: * After 2-3 weeks peripheral rodlets.Q - Within 48 hours of injury the endoneural tube, contain * Myelin sheath breaks down into oily droplets, It occurs nissl granules begins to varying no of developing fibril 8-32 days after injury.Q disintegrate (K/a * Medullary sheath begins to * Cells of the sheath of Schwann - divide mitoticallyQ & chromatolysis) develop in about 15 days & from cords of cells lying within the endoneurial tube - Golgi apparatus fragments completed within one year. (neurilemma) --> macrophages remove the degenerating - Cells swell * Repair of cell body (i.e. Nissl myelin & axis cylinder -s thus schwann cell cytoplasm - Neurofibril disappear & granules & golgi apparatus) --> gradually fills the neurilemma, this process is completed by nucleus displaced to cell begins about 20 days after 3 months. margin. nerve section & is completed * Hollow tube of neurilemma remains intact & K/a ghost tube. in 80 days. 1s1 change in cut nerve is - Axonal degeneration 2nd change in cut nerve is - Myelin degeneration
Schwann cells proliferation
Degeneration of myelin sheath
Chromatolysis
Degeneration of neurilema