Histologic studies of melanocytes of nail matrices with or without nail pigmentation were made in 15 specimens taken from 12 Japanese subjects. The following results were obtained: (1) Melanin granules were present in the normal nail matrix, (2) dopa-positive melanocytes were also present in the lower two to four layers of normal nail matrix, but few or none in the lowest layer, (3) histological findings of the nail matrix, corresponding to pigmented bands, revealed an increase in activity and number of dopa-positive melanocytes, (4) of five patients with pigmented band on nail, none was found to be nevoid in character.
Higashi N. Melanocytes of Nail Matrix and Nail Pigmentation. Arch Dermatol. 1968;97(5):570-574. doi:10.1001/archderm.1968.01610110078013