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.