Nervous Tissue - Classification of Neurons

Classification of Neurons

Neurons are classified both structurally and functionally.

Structural Classification Neurons are grouped structurally according to the number of processes extending from their cell body. Three major neuron groups make up this classification: multipolar (polar = end, pole), bipolar and unipolar neurons.

Multipolar Neurons (3+ processes)

These are the most common neuron type in humans (more than 99% of neurons belong to this class) and the major neuron type in the CNS

Bipolar Neurons

Bipolar neurons are spindle-shaped, with a dendrite at one end and an axon's at the other. An example can be found in the light-sensitive retina of the eye. They also rapidly grow.

Unipolar Neurons

Sensory neurons have only a single process or fibre which divides close to the cell body into two main branches (axon and dendrite). Because of their structure they are often referred to as unipolar neurons.