Abstract
The distribution of cholinesterases in the cranial and spinal sensory ganglia was investigated in the cat, guinea-pig, rat, mole and man using a modified Koelle's histochemical technique. It was found that the cytoplasm of the sensory nerve cells contained acetylcholinesterase in all species, but the concentration of the enzyme varied from cell to cell. Nerve fibers gave a negative acetylcholinesterase reaction in the cat and guinea-pig, and a weak to moderate positive reaction in the rat, mole and man. Non-specific cholinesterase was only found in the sensory ganglia of the cat and guinea-pig. In human sensory ganglia, it was found during the fetal life but not after birth. The sensory ganglia of the rat were found to be nearer to those of man than the ganglia of the cat or guinea-pig in respect of cholinesterase distribution. It is suggested that the variations in acetyl-cholinesterase activity among different nerve cells may signify the existence of several cell types in the sensory ganglia. The role of intracytoplasmic cholinesterase in the sensory nerve cells is discussed.