Studies on melanocytes III. Melanocytes in muscles of mastication

Giant melanocytes were observed in the masseter and temporalis muscles of all human fetuses and neonates examined, both Caucasian and Negro. These cells are invariably absent in adults of both races. A finding exactly opposite to that of the nasal mucosa where melanocytes are present in adulthood but uniformly lacking in fetal and neonatal material. In keeping with these observations, numerous primary melanomas of the nasal mucosa are documented but there is no case recorded of this tumor arising in the muscles of mastication. The extra epidermal distribution of melanocytes in vertebrates has been reviewed.