Melanin granule in skin window macrophages.

Pigment granules have been studied in macrophages of skin window preparations. These granules usually appeared blue with Romanowsky stains, and stained positively for melanin but negatively for iron. There were significantly more pigment granules per macrophage in sun-tanned individuals and in coloured subjects and in the latter, the granules were usually larger and darker. Presumably, the source of the melanin is damaged or degenerating pigment cells of the skin and reflects a normal in vivo phenomenon.