See also
 | Look up melanoblast in Wiktionary, the free dictionary. |
A melanoblast is a precursor cell of a melanocyte. These cells migrate from the trunk neural crest cells (in terms of axial level from neck to posterior end) dorsolaterally between the ectoderm and dorsal surface of the somites. [1]
| Look up melanoblast in Wiktionary, the free dictionary. |
Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer of the skin's epidermis, the middle layer of the eye, the inner ear, vaginal epithelium, meninges, bones, and heart. Melanin is a dark pigment primarily responsible for skin color. Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation. Thus darker skin tones have more melanosomes present than lighter skin tones. Functionally, melanin serves as protection against UV radiation. Melanocytes also have a role in the immune system.
Freckles are clusters of concentrated melaninized cells which are most easily visible on people with a fair complexion. Freckles do not have an increased number of the melanin-producing cells, or melanocytes, but instead have melanocytes that overproduce melanin granules (melanosomes) changing the coloration of the outer skin cells (keratinocytes). As such, freckles are different from lentigines and moles, which are caused by accumulation of melanocytes in a small area. Freckles can appear on all types of skin tones. Of the six Fitzpatrick skin types, they are most common on skin tones 1 and 2, which usually belong to North Europeans. However, it can be found in all ethnicities.
A birthmark is a congenital, benign irregularity on the skin which is present at birth or appears shortly after birth—usually in the first month. They can occur anywhere on the skin. Birthmarks are caused by overgrowth of blood vessels, melanocytes, smooth muscle, fat, fibroblasts, or keratinocytes.
The melanocyte-stimulating hormones, known collectively as MSH, also known as melanotropins or intermedins, are a family of peptide hormones and neuropeptides consisting of α-melanocyte-stimulating hormone (α-MSH), β-melanocyte-stimulating hormone (β-MSH), and γ-melanocyte-stimulating hormone (γ-MSH) that are produced by cells in the pars intermedia of the anterior lobe of the pituitary gland.
A melanosome is an organelle found in animal cells and is the site for synthesis, storage and transport of melanin, the most common light-absorbing pigment found in the animal kingdom. Melanosomes are responsible for color and photoprotection in animal cells and tissues.
PUVA is an ultraviolet light therapy treatment for skin diseases: eczema, psoriasis, graft-versus-host disease, vitiligo, mycosis fungoides, large plaque parapsoriasis and cutaneous T-cell lymphoma using the sensitizing effects of the drug psoralen. The psoralen is applied or taken orally to sensitize the skin, then the skin is exposed to UVA.
Neural crest cells are a temporary group of cells unique to vertebrates that arise from the embryonic ectoderm germ layer, and in turn give rise to a diverse cell lineage—including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia.
A lentigo is a small pigmented spot on the skin with a clearly defined edge, surrounded by normal-appearing skin. It is a harmless (benign) hyperplasia of melanocytes which is linear in its spread. This means the hyperplasia of melanocytes is restricted to the cell layer directly above the basement membrane of the epidermis where melanocytes normally reside. This is in contrast to the "nests" of multi-layer melanocytes found in moles. Because of this characteristic feature, the adjective "lentiginous" is used to describe other skin lesions that similarly proliferate linearly within the basal cell layer.
Rab27 is a member of the Rab subfamily of GTPases. Rab27 is post translationally modified by the addition of two geranylgeranyl groups on the two C-terminal cysteines.
'Piebaldism’ refers to the absence of mature melanin-forming cells (melanocytes) in certain areas of the skin and hair. It is a rare autosomal dominant disorder of melanocyte development. Common characteristics include a congenital white forelock, scattered normal pigmented and hypopigmented macules and a triangular shaped depigmented patch on the forehead. There is nevertheless great variation in the degree and pattern of presentation, even within affected families. In some cases, piebaldism occurs together with severe developmental problems, as in Waardenburg syndrome and Hirschsprung's disease.
Microphthalmia-associated transcription factor also known as class E basic helix-loop-helix protein 32 or bHLHe32 is a protein that in humans is encoded by the MITF gene.
Stem cell factor is a cytokine that binds to the c-KIT receptor (CD117). SCF can exist both as a transmembrane protein and a soluble protein. This cytokine plays an important role in hematopoiesis, spermatogenesis, and melanogenesis.
Smoker's melanosis is seen with the naked eye as a brown to black pigmentation of the oral tissue i.e. the gums, cheeks or palate as well as in larynx. It is most often seen in the lower labial gingiva of tobacco users. Most easily it is found in Caucasians, due to their lack of a genetically caused melanin pigmentation.
Endothelin-3 is a protein that in humans is encoded by the EDN3 gene.
Transcription factor SOX-10 is a protein that in humans is encoded by the SOX10 gene.
Amelanism is a pigmentation abnormality characterized by the lack of pigments called melanins, commonly associated with a genetic loss of tyrosinase function. Amelanism can affect fish, amphibians, reptiles, birds, and mammals including humans. The appearance of an amelanistic animal depends on the remaining non-melanin pigments. The opposite of amelanism is melanism, a higher percentage of melanin.
The trunk neural crest or truncal neural crest is one of the regions of neural crest in the embryo.
Tortoiseshell is a cat coat coloring named for its similarity to tortoiseshell material. Like calicos, tortoiseshell cats are almost exclusively female. Male tortoiseshells are rare and are usually sterile.
The melanocortin 1 receptor (MC1R), also known as melanocyte-stimulating hormone receptor (MSHR), melanin-activating peptide receptor, or melanotropin receptor, is a G protein–coupled receptor that binds to a class of pituitary peptide hormones known as the melanocortins, which include adrenocorticotropic hormone (ACTH) and the different forms of melanocyte-stimulating hormone (MSH). It is coupled to Gαs and upregulates levels of cAMP by activating adenylyl cyclase in cells expressing this receptor. It is normally expressed in skin and melanocytes, and to a lesser degree in periaqueductal gray matter, astrocytes and leukocytes. In skin cancer, MC1R is highly expressed in melanomas but not carcinomas.
Rhododendrol (RD) also called 4-[(3R)-3-hydroxybutyl]phenol (systemic name), is an organic compound with the formula C10H14O2. It is a naturally occurring ingredient present in many plants, such as the Rhododendron. The phenolic compound was first developed in 2010 as a tyrosinase inhibitor for skin-lightening cosmetics. In 2013, after rhododendrol reportedly caused skin depigmentation in consumers using RD-containing skin-brightening cosmetics, the cosmetics were withdrawn from the market. The skin condition, caused by RD, is called RD-induced leukoderma. Rhododendrol exerts melanocyte cytotoxicity via a tyrosinase-dependent mechanism. It has been shown to impair the normal proliferation of melanocytes through reactive oxygen species-dependent activation of GADD45. It is now well established that rhododendrol is a potent tyrosinase inhibitor.
 | This developmental biology article is a stub. You can help Wikipedia by expanding it. |