A Nissl body (or Nissl granule or tigroid body) is a large granular body found in neurons. These granules are rough endoplasmic reticulum (with free ribosomes) and are the site of protein synthesis. It was named after Franz Nissl, German neurologist (1860-1919)[1].
Nissl bodies can be demonstrated by a method of selective staining developed by Nissl (Nissl staining), using an aniline stain to label extranuclear RNA granules. This staining method is useful to localize the perikaryon, cell body, as it can be seen in the Soma (biology) and dendrites of neurons, though not in the axon or axon hillock. Due to RNA's basophilic (lat. "base-loving") properties it is stained blue by this method.
Nissl bodies show changes under various physiological conditions and in pathological conditions they may dissolve and disappear (karyolysis).
They are thought to be involved in the synthesis of neurotransmitters such as acetylcholine.
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