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melatonin
(redirected from Melanopsin)

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melatonin: see pineal gland pineal gland , small organ (about the size of a pea) situated in the brain. Long considered vestigial in humans, the structure, which is also called the pineal body or the epiphysis, is present in most vertebrates.
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melatonin

Hormone secreted by the pineal gland of most vertebrates. It appears to be important in regulating sleeping cycles; more is produced at night, and test subjects injected with it become sleepy. Melatonin may be involved in seasonal affective disorder. In mammals other than humans, melatonin may act as a cue to breeding and mating in season.

melatonin [‚mel·ə′tōn·ən]
(biochemistry)
A hormone secreted by the pineal gland that acts on melanophores in the skins of amphibians and reptiles to concentrate the melanin in the center of the cells, lightening the body surface; in higher vertebrates it conveys information about time that influences reproduction and circadian physiology.
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Focusing their efforts on the melanopsin light sensor, which is responsible for sensing day and night but barely involved - in mammals, at least - in seeing images, Yau's team looked for melanopsin-containing cells in other vertebrates, and found some in the retinal horizontal cells in goldfish and catfish.
Scientists find cell in fish that can sense light and contribute to ... by Asian News International
More specifically, melanopsin is found in a subtype of intrinsically photoreceptive retinal ganglion cells (ipRGCs) (Berson et al.
Meeting report: the role of environmental lighting and circadian ... by Stevens, Richard G.; Blask, David E.; Brainard, George C.; Hansen, Johnni; Lockley, Steven W.; Prove / Environmental Health Perspectives
2006) reported the discovery of a melanopsin in retinal ganglion cells of chickens that functions in the circadian rhythm and pupillary light reflex.
Evolution: do the eyes have it? by Reinbold, Stephen L. / Forum on Public Policy: A Journal of the Oxford Round Table
 
 
 
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