Medical Sciences 3999A/B/Y Lecture Notes - Lecture 20: Peristalsis, Sphincter, Glycogenolysis
16 Feb 2020
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Whole cell - size increases due to water entering cytoplasm. Cytoplasm: nissl substance disappears = chromatolysis and fragments. Nucleus: often moves to edge of the cell (eccentric) Axon - involves whole of the axon, distal to the point of damage and a small part of the proximal. Endoneurial tube: collapses due to disappearance of axoplasm. Macrophages: attracted to area of damage by chemotaxis --> removes myelin droplets and axoplasm by phagocytosis (schwann cells may assist with lytic enzymes) Cell body - reversal of all degeneration changes: Schwann cell: proliferate in proximal & distal stumps of axon --> subsequently ceases. Reflates and bridges the gap between 2 stumps. Axon: sprouts from healthy axon which remained in proximal stump. Sprouting grow distally into and across gap between the two axon stumps. Uses schwann cell columns as guide line, until reaching distal stump. Sometimes grow sideways in error --> loses their way. Myelin sheath: reforms starting nearest cell body --> towards axon terminals.
