Serotonin and opsin immunoreactivities in the developing pineal organ of the three-spined stickleback, Gasterosteus aculeatus L.

Research output: Contribution to journalArticle


5-hydroxytryptamine (5-HT, serotonin)- and opsin-immunoreactive sites were studied in the developing pineal complex of the stickleback, Gasterosteus aculeatus L., by use of light-microscopic indirect immunoperoxidase techniques. 5-HT immunoreactivity first occurs in the pineal organ at the age of 80 h after fertilization and appears to be localized in cells of the photoreceptor type. The outer segments of a few pineal photosensory cells exhibit opsin immunoreactivity at the age of 84 h after fertilization. The number of cells seems to increase until the pineal organ is completely developed. The increase in the number of 5-HT immunoreactive perikarya runs parallel in time to that of the opsinimmunoreactive outer segments. The cells of the parapineal organ show neither opsin nor 5-HT immunoreactivity. The retina of the embryonic stickleback does not display opsin immunoreactivity until after hatching, which takes place about 144 h after fertilization. These results suggest, in the three-spined stickleback, an earlier light-perception capacity for the developing pineal organ than for the retina.


  • Theo van Veen
  • Peter Ekström
  • Lena Nyberg
  • Bertil Borg
  • Ingeborg Vigh-Teichmann
  • Bela Vigh
External organisations
  • Justus Liebig University Giessen
  • Lund University
  • Semmelweis University
Research areas and keywords


  • Development, ontogenetic, Immunohistochemistry, Opsin, Photoreceptor cells, Pineal complex (pineal and parapineal organs), Serotonin (5-HT), Teleost (Gasterosteus aculeatus)
Original languageEnglish
Pages (from-to)559-564
Number of pages6
JournalCell and Tissue Research
Issue number3
Publication statusPublished - 1984 Aug 1
Publication categoryResearch