title: Circadian organization in lizards: the role of the pineal organ.
abstract: After pinealectomy, the iguanid lizard Sceloporus olivaceus exhibits a "splitting" of the circadian activity rhythm into two components, marked changes in the period of the rhythm, or arrhythmicity. These effects are consistent with either of two hypotheses: (i) The pineal organ is a coupling device between circadian oscillators in a multioscillator system, or (ii) the pineal organ is itself a master oscillator, which entrains other circadian oscillators and imposes its frequency upon them.
mesh_terms: D000818:Animals; D001683:Biological Clocks; D002940:Circadian Rhythm; D003624:Darkness; D008027:Light; D008116:Lizards / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D009799:Ocular Physiological Phenomena; D010870:Pineal Gland / Q000502:physiology*