NEUROGLIA Specialized form of connective tissue cells found

NEUROGLIA

• Specialized form of connective tissue cells found in association with nervous system. • They are not excitable and they cannot conduct impulses. • Number of neuroglia is much more than neurons. • Unlike the neurons they retain the ability to divide and multiply throughout life.

Functions: • Responsible for the fixation of the neurons within the nervous system. • Phagocytosis. • Nutrition. • Myelin sheath formation in CNS. • They acts as a “set point” for regulation of various neural control mechanisms because of their fixed metabolism.

Types of Neuroglia: 1. Microcytes/Mesoglia. 2. Astrocytes 3. Ependymal cells 4. Oligodendroglia/Oligodendrocytes. 5. Satellite cells. 6. Schwann cells.

Microglia: • Derived from the Mesoderm. • Shows Phagocytic action. • Found in the grey matter of the CNS.

Astrocytes. Found scattered throughout the CNS. Both in grey and white matters. Two types: • Protoplasmic Astrocytes. • Fibrous Astrocytes.

Protoplasmic Astrocyte Found mostly in Grey matter

Functions: • Provides nutrition and remove the waste products. • Support the neuron. • Anatomical basis of blood brain barrier. • They act as a electrical insulator.

Ependymal cells: They resemble epithelial cells and line the ventricles of the brain and central canal of spinal cord. Function: Secretion of Cerebro - spinal fluid.

Oligodendrocytes: Present both in grey and white matter. Function: To lay down myelin sheath around the nerve fiber within the brain

Satellite cells: Encapsulate the dorsal and cranial nerve ganglion cells. Function: Regulate their micro environment(Barrier formation).

Schwann cells: They help in the formation of myelin sheath around the peripheral neurons.