Histochemical studies on the accessory body of Cajal in neurones of the cat

The accessory body of Cajal is an argyrophil body measuring between 0.5 μ and 1.0 μ in diameter and is present in the nuclei of most neurones of the cat. Histochemically, the accessory body contains small amounts of bound lipids and proteins containing tyrosine, NH 2 groups and arginine. It does not possess detectable amounts of nucleic acids (RNA or DNA), tryptophan, histidine or amino acids with free SH groups. The accessory body of Cajal differs from the sex chromatin and the nucleolus in several important respects. Its role in cellular physiology is unknown.