A neuron is the structural and functional unit of the nervous tissue. A neuron is made up of cyton or cell body and cytoplasmic extensions or processes. 

1. Cyton: The cyton or cell body contains granular cytoplasm called neuroplasm and a centrally placed nucleus. The neuroplasm contains mitochondria, Golgi apparatus, RER and Nissl’s granules.

2. Cytoplasmic extensions or processes: The fine branches of a dendron are called dendrites. Dendrites carry an impulse towards the cyton. 

a. Dendron: They are short, unbranched processes.

b. Axon: It is a single, elongated and cylindrical process. The axon is bound by the axolemma. The protoplasm or axoplasm contains large number of mitochondria and neurofibrils. 

The axon is enclosed in a fatty sheath called the myelin sheath and the outer covering of the myelin sheath is the neurilemma. Both the myelin sheath and the neurilemma are parts of the Schwann cell. The myelin sheath is absent at intervals along the axon at the Node of Ranvier. 

The fine branching structure at the end of the axon (terminal arborization) is called telodendron. 

1. Nissl’s Granules 

2. Nissl’s granules are large granular bodies, found in neurons. These granules are made up of rough endoplasmic reticulum (RER) and free ribosomes (site of protein synthesis). 

3. It was named after Franz Nissl, a German neuropathologist who invented the Nissl staining method.