The nucleus contains fine particles of chromatin and the female nuclei contain a large chromatin mass, the sex chromosome or Barr body. This is usually found against the nuclear membrane. The Nucleus - There is much variability from one tissue to another in the size, density and shape of cell nuclei. Certain cells, large motor neurons for example, have very large nuclei with prominent nucleoli. Be sure that you understand which is the nucleus and which is the nucleolus of these cells.
Some cells have very irregularly-shaped nuclei.
Fibrils - certain cells contain linearly oriented protein molecules in the form of fibrils within the cell cytoplasm. The large granular cytoplasmic masses found in the cytoplasm of large multipolar neurons are called Nissl bodies. The nuclei are usually located at the periphery of the cell, while the apex contains fine granules. Slide demonstration is a PAS stained liver slide. Note the red-staining deposits within the cell cytoplasm.