Dorsal Root Ganglia

The axons and cell bodies of a dorsalRelating to the back side of the body. root ganglionA cluster of neuron cell bodies located in the peripheral nervous system (PNS). can be seen here in cross section A cut or slice of the body or an organ for study..

Each spinal nerve has two dorsal root ganglia – one on the left and one on the right.  The dorsal (or posterior) root branches off of the spinal nerve as you travel medially into the spinal cordThe central nervous system structure that relays signals between the brain and body..  Just before the dorsal root enters the spinal cord is a bulbous dorsal root ganglion.  Conversely, there is no ventralRelating to the front or belly side of the body. root ganglion. This absence allows you to easily tell which is the dorsal direction. You can also identify which is the ventral direction on a transverse cut of the spinal cord. 

The dorsal root carries axons of sensory neuronsNeurons that carry information from sensory receptors to the CNS. only.  These neuronsThe functional cells of the nervous system that transmit signals. are unipolar. Their cell bodyThe central part of a neuron containing the nucleus and organelles. is located off of the axon. It is not at the same location as the dendritesBranch-like extensions from a neuron that receive signals from other neurons..  The axon of the unipolar neuronA neuron with one process that splits into peripheral and central branches, common in sensory neuron enters the spinal cord. It synapses with other neurons in the gray matterThe inner portion of the spinal cord composed mostly of neuron cell bodies and synapses.. The unipolar cell bodies are aggregated together in the dorsal root ganglion.  The cell bodies are not myelinated. Therefore, dorsal root ganglia can be better visualized by a silver stain, as is with most nervous tissue.