Dorsal Root Ganglion
• They are also called as sensory ganglion.
• Present in dorsal root of spinal nerve,
• Contains first order sensory neurons.
• Thick connective tissue capsule seen.
• Pseudounipolar ganglion cells-large cells with central nucleus, arranged in groups.
• Satellite cells are more prominent forming a capsule around ganglion cells. It helps in nourishment and insulation.
• Bundles of parallel running myelinated and unmyelinated nerve fibers seen.
Symphathetic Ganglion
• Located in sympathetic trunk.
• Belong to autonomic nervous system, contains cell bodies of postganglionic sympathetic neurons.
• Thin connective tissue capsule present.
• Multipolar ganglion cells-small in size, with eccentric nucleus. Scattered between nerve fibers.
• Few satellite cells surround the ganglion cells and helps in nourishment and insulation
Optic Nerve
• It is the second cranial nerve, a sensory nerve.
Developmentally it is an outgrowth from brain.
. It has meningeal coverings similar to brain-dura mater, arachnoid, pia mater.
• Optic nerve contains myelinated axons of ganglion cells of retina.
Axons grouped as bundles or fascicles by connective tissue extending from pia matter.
Axons are myelinated by the oligodendrocytes.
• Central artery, branch of ophthalmic artery is an end-artery, is accompanied by central vein of retina,
Peripheral Nerve
• Peripheral nerves are formed by bundles of axons which may be myelinated or non-myelinated.
• Nerve fibers are surrounded by supporting cells called Schwann cells, forming a sheath called neurilemma.
• In myelinated nerve fibers the Schwann cell undergo spiraling around the axon forming the fatty myelin sheath whereas in unmyelinated fibers they only form the neu-
rilemma
• Part of axon between two adjacent Schwann cells not covered with myelin is called nodes of Ranvier, helps in fast conduction of impulses.
• Each myelinated axon is surrounded by connective tissue endoneurium.
• Fascicles of nerve fibers surrounded by perineurium.
• Outermost covering of nerve fiber is epineurium.