Dorsal root ganglia (DRG)

Location of unipolar primary sensory neurons contained in nodules or swellings, lying lateral and dorsal to the dorsal roots the spinal cord.  Looking like a golf ball on a tee, they have concentrically located nuclei (see figure below).  In sensory ganglia, there are no synaptic contacts between neurons.   

Dorsal roots: sensory axons (blue) pass into the dorsal root ganglia where their cell bodies are located, and from here into the spinal cord to terminate on muscle spindles. All motor axons (red) pass into the ventral roots before uniting with the sensory axons to form spinal ‘mixed’ nerves to terminate on motor end plates.   

See Axon, Dorsal roots, Ectoderm, Ganglia, Motor end plate, Muscle spindle, Neural crest, Neuron, Peripheral nervous system, Spinal cord, Ventral roots