The synthetic hormone works by stimulating pigment cells in the skin, causing them to produce more of the melanin that gives skin its colour.

They arise because of errors in building the fine structure of the skin from blood vessel pigment cells and other cells.

They're caused by either by clusters of pigment cells, or abnormal blood vessels under or inside the skin.

An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells.

The retina comprises numerous pigment cells and photoreceptors; the latter are easily modified flagellated cells, whose flagellum membranes carry a photosensitive pigment on their surface.

Phycobilins are also closely related to the chromophores of the light-detecting plant pigment phytochrome, which also consist of an open chain of four pyrroles.

The plant pigment phytochrome was discovered using a spectrograph that used living plants as the detector.

Excessive consumption of lycopene, a plant pigment similar to carotene and present in tomatoes, can cause a deep orange discoloration of the skin.

Healthy chickens absorb more plant pigments from their diet.

Plant pigments include a variety of different kinds of molecules, including porphyrins, carotenoids, and anthocyanins.

Its team have been working on variations in the distribution of skin pigment (melanin), hyperpigmentation and other skin blemishes and blotches.

There are like remarks on topics such as the nature of skin pigment and his attraction to decorative interiors.

When these levels fall, melanoma cells stop dividing and form into a round shape, like a normal skin pigment cell.

The varied and often vivid colours of echinoderms are produced by the action of skin pigment cells.

Their skin pigment ranges from a deep red through nearly any shade of orange to yellow.