A melanin-containing nucleus associated with the superior cerebellar peduncle in man. Cytomorphometric analysis

A melanin-containing nucleus in the oral lateral pontine tegmentum is morphometrically described. The griseum is circumscript and well defined, being closely applied to the ventrolateral aspect of the superior cerebellar peduncle, and within the brachiolemniscal trigone. The nucleus contains two statistically discrete cell populations, small pigmented and small nonpigmented perikarya, both of which demonstrate pleomorphic profiles. The extranuclear pigment granula resemble those of the pigmented cells of the ceruleus complex, substantia nigra, and the dorsal motor nucleus of the vagus, and are melanin. In man this griseum is found in the region corresponding to an area in close proximity and in some cases continuous to A7 of Dahlström and Fuxe, also described by numerous investigators in subhuman primates. It is not identical with the nucleus of KOLLIKER and FUSE. It is proposed that the nucleus may be a component of the brain stem catecholamine system in man.