Cell Body

The cell body contains the nucleus and the perikaryon (cytoplasm). The nucleus has a prominent nucleolus and a variable amount of chromatin. The perikaryon comprises the Nissl bodies and the argyrophilic fibrils (see Fig 2.1). The neurons in the compact zone of the substantia nigra, locus ceruleus, and dorsal nucleus of vagus contain melanin pigments. The perikaryon, at ultrastructural level, contains a variety of subcellular organelles: a rough endoplasmic reticulum with ribosomes (Nissl bodies in light microscopy), a smooth endoplasmic reticulum, Golgi apparatus, mitochondria, peroxi-somes, lysosomes, and cytoskeletal organelles. Three major classes of cytoskeletal organelles are the microtubules, the intermediate filaments, and the microfilaments, all associated with proteins. The microtubules are associated with tau proteins, the neurofilaments (argyrophilic fibrils in light microscopy) with neuron-specific peptides, and the microfilaments with actin.

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