Fine structure of neuronal spherical arginine-rich bodies of substantia nigra and locus coeruleus in the human brain.

Neuronal spherical bodies, rich in arginine, of catecholamine neurons in man display staining reactions of mitotic chromosomes and myelin basic protein. They show a unique fine structure and density in the EM after phosphotungstic acid hematoxylin block-staining. With an electron-lucent core, a dense rim and a limiting double membrane they stand out and are differentiated from all other neuronal inclusions, especially melanin. Protein bodies were found inside mitochondria, where they apparently originate as small globules in the matrix. They later enlarge into spheres by obliterating the cristae, but retaining the outer membranes of the parent mitochondrion. The arginine-rich basic protein of the spherical bodies, it is argued, may be involved in the modulation of excitability of the catecholamine neurons in man.