Innmunoelectron-microscopic investigation of the subcellular localization of pinopsin in the pineal organ of the chicken

Kanjun Hirunagi*, Shizufumi Ebihara, Toshiyuki Okano, Yoko Takanaka, Yoshitaka Fukada

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


Pinopsin is a photoreceptive molecule cloned from the chicken pineal organ. An antibody highly specific for pinopsin was applied in light- and electron-microscopic immunocytochemical studies of the pineal organ of 1 to 2-month-old chickens. Intense immunoreactivity was found in the follicular lumen at the light-microscopic level. In addition, small immunoreactive spherical or fibrous structures were diffusely distributed at the parafollicular aspect of the pineal organ. To identify immunoreactive elements precisely, we used pre-embedding immunoelectron microscopy. These studies revealed immunoreactive outer segments of pinealocytes arranged closely side by side in the follicular lumina. The thin initial portion of the outer segment arose from a basal body located in the inner segment. Immunoreactive pear-shaped outer segments occupied small lumina. Follicular lumina displayed immunonegative arrays of whorl-like lamellar membranes. Occasionally, these immunonegative structures were surrounded by immunoreactive concentric lamellar complexes. In the parafollicular pineal parenchyma, long slender cilium-like structures or enlarged cilia and concentric lamellar arrays showed intense immunoreactivity. All immunoreactive structures observed in this study were considered to represent outer segments of pinealocytes of the chicken pineal organ.

Original languageEnglish
Pages (from-to)235-241
Number of pages7
JournalCell and Tissue Research
Issue number2
Publication statusPublished - 1997
Externally publishedYes


  • Chicken
  • Immunocytochemistry
  • Photopigment
  • Pineal organ
  • Pineal photoreceptors
  • Pinealocytes
  • Pinopsin
  • Sensory structures

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology


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