Nissl bodies
microscopic particles, consisting of granular endoplasmic reticulum and ribosomes, found in large numbers in the cell bodies of neurons. Nissl bodies can be stained by toluidine blue (Nissl stain), which allows measurement of cell-body size and the density of neurons in different regions of the nervous system. Also called Nissl granules; Nissl substance; tigroid bodies. [Franz Nissl (1860–1919), German neuropathologist]