Photoreception and circadian clock system of the chicken pineal gland

Toshiyuki Okano, Yoshitaka Fukada*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

36 Citations (Scopus)


Chicken pinealocytes contain three major components of the circadian clock system: 1) a self-sustained oscillator, 2) a photic-input pathway to the oscillator, and 3) an overt output represented by the rhythmic production of melatonin. Even under cultured conditions of isolated pineal gland or dissociated pinealocytes, the input-oscillator-output functions are well maintained. Because of these experimental advantages, chicken pineal gland has been one of the best models for the study of the circadian clock system. Since the finding of a pineal-specific photoreceptive molecule, pinopsin, we have characterized the endogenous phototransduction pathway in the pinealocytes. On the other hand, despite the long history of chick pineal research, the molecular mechanism underlying the pineal clock oscillation has been largely unknown. Our recent characterization of the chick pineal clock genes strongly suggests that they constitute a transcription/translation-based autoregulatory feedback loop, which is very similar to that generating circadian rhythmicity in mammalian SCN.

Original languageEnglish
Pages (from-to)72-80
Number of pages9
JournalMicroscopy Research and Technique
Issue number1
Publication statusPublished - 2001 Apr 1
Externally publishedYes


  • Circadian rhythm
  • G-protein
  • MAPK
  • Melatonin
  • Pinopsin

ASJC Scopus subject areas

  • Anatomy
  • Histology
  • Instrumentation
  • Medical Laboratory Technology


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