Extraretinal Light Perception: Entrainment of the Biological Clock Controlling Lizard Locomotor Activity

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Science  09 Oct 1970:
Vol. 170, Issue 3954, pp. 190-193
DOI: 10.1126/science.170.3954.190


The circadian activity rhythm of the iguanid lizard Sceloporus olivaceus can be entrained by light cycles whether or not the animals have eyes. Removal of the pineal organ and parietal eye in blinded lizards does not prevent entrainment. Our data demonstrate the existence of an extraretinal photoreceptor which can mediate entrainment of a biological clock in reptiles.

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