Nervous tissue part 2.pdf

Nervous tissue Part 2 Glial cells (neuroglia Glial cells (neuroglia): Neuroglia (in CNS): Astrocytes Protoplasmic astrocytes large cells with many short processes around blood vessels.. Function: nutrition of neurons. Fibrous astrocytes : large cells with few long processes containing micro-filament...

Nervous tissue Part 2 Glial cells (neuroglia Glial cells (neuroglia): Neuroglia (in CNS): Astrocytes Protoplasmic astrocytes large cells with many short processes around blood vessels.. Function: nutrition of neurons. Fibrous astrocytes : large cells with few long processes containing micro-filaments. Function: support of neurons Microglia small spindle-shaped cells characterized by. Function: phagocytosis of micro-organisms in CNS Oligo-dendrocytes (in both matters): small cells with processes. Function: myelin sheath formation. Ependymal cells: simple cubical ciliated epithelial cells which line brain ventricles and central canal. Function: CSF formation. Neuroglia (in PNS): Satellite cells: small cells around neurons Function: nutrition of neurons. Schwan cells: around axons of peripheral nerves. Function: myelin sheath formation and axon regeneration Structure of a nerve A nerve is composed of bundles (Fascicles) of nerve fibers (axons). The nerve as a whole is enclosed in a dense connective tissue (DCT) sheath called the epineurium. Each fascicle is wrapped in a layer of CT called perineurium. Individual nerve fibers are enveloped in a thin CT. layer called endoneurium. Myelination Some nerve fibers are myelinated and others not myelinated Myelin sheath: A lipo-protein substance that speed transmission of nerve impulses. It is formed by by oligo- dendrocytes (in CNS). The cell sends processes which become flattened and wrap the axons resulting in various degrees of myelination. In this case the myelinated fiber is located far from the body of the oligodendroglia In PNS It is done by Schwan cells Schwan cells rotate around the axon leading to myelin sheath formation. Myelin sheath is formed from lipid and protein dissolved with Hx and E staining Appeared black with osmic acid stain THANK YOU