Chromatophores are largely responsible for generating skin and eye colour in poikilothermic animals and are generated in the neural crest during embryonic development. Mature chromatophores are grouped into subclasses based on their colour under white light:

xanthophores (yellow): contain yellow pigments in the forms of carotenoids
erythrophores (red): contain reddish pigments such as carotenoids and pteridine
melanophores (black/brown): contain black and brown pigments such as the melanins
cyanophores (blue): limited taxonomic range but found in some fish and amphibians

Structural colours
Animals can also appear coloured due to structural colour, the result of coherent scattering perceived as iridescence. The structures themselves are colourless. Light typically passes through multiple layers and is reflected more than once. The multiple reflections compound one another and intensify the colours. Structural colour differs according to the observers position whereas pigments appear the same regardless of the angle-of-view. Animals that show iridescence include mother of pearl seashells, fish, and peacocks. These are just a few examples of animals with this quality, but it is most pronounced in the butterfly family. iridophores (reflective/iridescent): sometimes called "guanophores", reflect light using plates of crystalline chemochromes made from guanine
leucophores (reflective white): found in some fish, utilize crystalline purines (often guanine) to produce a reflective, shiny, white colour. Plant colouration
The primary function of pigments in plants is photosynthesis, which uses the green pigment chlorophyll along with several red and yellow pigments including porphyrins, carotenoids, anthocyanins and betalains. Definition
Definitions of albinism vary and are inconsistent.
A personal lubricant can be applied to the vaginal opening, the penis, or both, to augment the naturally produced lubrication and prevent or reduce the discomfort or pain. More rarely, a vaginal suppository may be inserted prior to intercourse. Oil-based lubricants can weaken latex and reduce the effectiveness of condoms, latex gloves, or dental dams as either forms of birth control or for protection from sexually transmitted diseases, so water- or silicone-based lubricants are often used instead. The use of an artificial lubricant can make sexual intercourse less painful for a woman, but does not address the underlying cause of the vaginal dryness itself. Both canola oil and mineral oil are recommended by the American Society for Reproductive Medicine as fertility-preserving types of personal lubricant. Dry sex
Some people practice dry sex, which involves the removal of vaginal lubrication in some way. The rationale for the practice seems to be for cleansing purposes and to enhance the sexual pleasure of the penetrating partner. However, besides making sexual intercourse painful for the female, the practice is believed to increase the risk of transmitting sexually transmitted diseases for both partners, such as HIV, whose risk of transmission is increased by lacerations in the vaginal tissue resulting from the lack of lubrication. See also
References
External links

Mayo Clinic - Vaginal dryness