Skin and hair pigmentation are two of the most easily visible examples of human phenotypic variation. Selection-based explanations for pigmentation variation in humans have focused on the relationship between melanin and ultraviolet radiation, which is largely dependent on latitude. In this study, skin and hair pigmentation were measured as the melanin (M) index, using narrow-band reflectance s...

Ocular pigmentation in white cats with blue and yellow eyes and in Siamese cats was examined ophthalmoscopically and histologically. Yellow-eyed white cats had entirely normal ocular pigmentation. Blue eyes of white cats had normal pigmentation of the iridial and retinal pigment epithelia but no stromal pigmentation of the iris or choroid. This deficit is apparently due to the absence of stroma...

The pigmentation of human gingival tissue is derived from melanin granules, which are synthesized in the melanosomes of melanocytes [1,2]. The nicotine present in tobacco activates melanocytes to promote melanin secretion [3]. Therefore, the melanin pigmentation in gingival tissues has a strong correlation with smoking [4,5]. In 1977, Hedin et al. [5] first reported that smokers showed more pig...