Pseudounipolar

Pseudounipolar neurons are a class of sensory neurons in the peripheral nervous system characterized by a single, short process that emerges from the cell body and quickly divides into two branches: a peripheral process that extends to sensory receptors in the periphery and a central process that enters the central nervous system. Although they appear to have one projection, the two branches function as a continuous axon, with the soma typically located in a dorsal root ganglion or in sensory ganglia of certain cranial nerves.

Development and structure are distinctive: these neurons originate from neural crest cells. During maturation, the initially bipolar neuron develops a single process that soon splits into a peripheral and a central branch, giving the pseudounipolar morphology. In adults, their cell bodies reside mainly in dorsal root ganglia of the spinal nerves and in the sensory ganglia of some cranial nerves.

Functionally, pseudounipolar neurons convey somatic and visceral sensory information toward the central nervous system. The peripheral process relays signals from receptors such as those for touch, proprioception, pain, and temperature, while the central process transmits impulses into the spinal cord or brainstem for processing.

Distribution and clinical relevance are tied to the dorsal root and cranial sensory ganglia. These neurons support rapid, direct transmission of sensory information and can be involved in neuropathies and other sensory disorders. Pathologies affecting dorsal root ganglion neurons, including diabetic neuropathy or herpes zoster reactivation, can manifest as sensory symptoms in peripheral regions.