Elementary particles in isolated rat liver and spleen nuclear membranes.

Elementary spherical particles similar to those described in the mitochondria are found in isolated rat liver and spleen nuclear membranes. The particles are characterized by electron microscopy of sections and preparations negatively stained with phosphotungstic acid or with the ATPase histochemical reaction product. The particles exhibit adenosine triphosphatase activity and have a mushroom-like shape with a sphere about 85-90 angstrom in diameter attached to inner face of the inner nuclear membrane by a stalk about 50 angstrom in length and 35 angstrom in diameter.