It arises from a one embryonic cell known as neuroblast
Types of neuron:
According to number of process¬
(a) Unipolar: Only axon is there. e.g. mesencephalic nucleus.
(b) Pseudounipolar: Only axon is there but it gets seperate to form dendron also." e.g. sensory ganglia.
(c) Non-polar: Only cyton is there. e.g. Hydra and other cnidarians.
(d) Bipolar: One axon and one dendron is there. e.g. retinal and cochlear ganglia.
(e) Multipolar: One axon and various dendrons are there.
e.g. most of the neuron of the body.