n pl :  discrete granular bodies of variable size that occur in the cell body and dendrites but not the axon of neurons, are composed of RNA and polyribosomes, are stained with basic dyes (as methylene blue), and give a striped appearance to the cell - called also Nissl granules , tigroid substance 
 
Nissl, Franz (1860-1919), German neurologist. Nissl discovered a granular basophilic substance that is found in the nerve cell body and the dendrites. He published his research in 1894, and since then the granules have come to be known as Nissl bodies or Nissl granules. Also known for his many contributions to the preparation and microscopic inspection of nervous tissue, he used methylene blue or toluidine blue dyes in order to achieve maximum delineation of cellular structure.
 
 
 
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