Nissl bodies, also known as Nissl substance or Nissl granules, are large granular structures found in the cell body and dendrites of neurons. They are composed of rough endoplasmic reticulum (RER) and free ribosomes, which are essential for protein synthesis. The staining properties of Nissl bodies, due to their high RNA content, make them readily visible under a microscope when stained with basic dyes, such as cresyl violet or toluidine blue.
