The normal products of the murine Steel (Sl) and Dominant white spotting (W) genes are essential for the development of melanocyte precursors, germ cells, and hematopoietic cells. The Sl locus encodes stem cell factor (SCF), which is the ligand of c-kit, a receptor tyrosine kinase encoded by the W locus. One allele of the Sl mutation, Sl17H, exhibits minor hematopoietic defects, sterility only ...

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 aim of this study was to estimate how many blastomeres of the 4-cell mouse embryo contribute cells to the embryo proper and finally to the animal. To this end, 4-cell embryos of pigmented and albino genotypes were disaggregated and single blastomeres (henceforth called '1/4' or 'quarter' blastomeres) were reaggregated in the following combinations: one 'pigmented' blastomere + three 'albino...

The neural crest (NC) represents multipotent cells that arise at the interphase between ectoderm and prospective epidermis of the neurulating embryo. The NC has major clinical relevance because it is involved in both inherited and acquired developmental abnormalities. The aim of this study was to establish an experimental platform that would allow for the integration of human NC cells (hNCCs) i...

Introduction Oilseed rape is a worldwide major oil crop that also supplies oil-free meal with high protein content (38-40%) and well-balanced amino acid composition. Currently, the quality of oilseed rape meal is still altered by secondary metabolites such as procyanidins. These compounds are flavonoid end-products that accumulate specifically in the seed coat during seed embryogenesis and matu...

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...

OBJECTIVE Passive smoking leads to melanin pigmentation on gingiva. However, documentation of gingival pigmentation and salivary amylase activity in passive smokers relative to the duration of exposure to environmental tobacco smoke (ETS), is incomplete and requires further investigation. Thus, this study aimed to assess effects of ETS exposure on gingival pigmentation in young adults. In addit...

The small GTPase Rac1 is ubiquitously expressed in proliferating and differentiating layers of the epidermis and hair follicles. Previously, Rac1 was shown to regulate stem cell behaviour in these compartments. We have asked whether Rac1 has, in addition, a specific, stem-cell-independent function in the regulation of terminal hair follicle differentiation. To address this, we have expressed a ...