Dorsal Root Ganglion
Histology of the Dorsal Root Ganglion
Many of the cell bodies of the sensory and motor neurons of the peripheral neves are grouped into nodules or swellings called ganglia. There are two major types of ganglia in the peripheral nervous system: the craniospinal ganglia contain the cell bodies of sensory neurons of cranial and spinal nerves. The autnomic ganglia of the autonomic nervous system contain the cell bodies of the motor neurons of autonomic nerves.
The Ganglia of the Spinal Nerves - The Dorsal Root Ganglia
Each of the spinal nerves is equipped with a spinal ganglion, commonly called a dorsal root ganglion. The dorsal root ganglion is a swelling found along the dorsal root of the nerve. The dorsal root is one of two nerve roots associated with each spinal nerve. Through the dorsal root, pseudounipolar sensory axons continue, exclusively, from the nerve, to the spinal cord, entering the spinal cord along the cord's dorsolateral surface. The dorsal root ganglion contains the cell bodies of these pseudounipolar sensory neurons. The other nerve root, the ventral root, contains the axons of the large multipolar motor neurons. These axons originate at the cell bodies in the spinal cord and pass through the ventral root, exclusively, before entering the mixed nerve.
The cell bodies of the pseudounipolar sensory neurons located in the dorsal root ganglion are conspicuous spherical structures. They characteristically lack dendrites. Unlike motor neurons, the plasma membrane of pseudounipolar neurons is not directly involved in the integration or conduction of the sensory nerve impulse. Therefore each cell body is electrically insulated by small supportive cells called satellite cells.