Pineal neurons projecting to the brain of the rainbow trout, Salmo gairdneri Richardson (Teleostei) - In-vitro retrograde filling with horseradish peroxidase

Research output: Contribution to journalArticle


The morphology of intrapineal neurons that give rise to the pineal tract and project to the brain in the rainbow trout was visualized by the use of neuronal backfilling with horseradish peroxidase (HRP). The tracing was performed on excised pineal organs under in-vitro conditions at 4° C, with filling times ranging from 6 to 24 h. Large multipolar, bipolar and unipolar neurons were visualized in the rostral tip of the pineal organ ("pineal ganglion"). These neurons possessed extended dendritic trees participating in the formation of a circumscribed neuropil-like area. Throughout the pineal organ small bipolar elements were the most ubiquitous type of neuron, however, with markedly smaller numbers in the proximal portion of the pineal end-vesicle. In the pineal stalk, some bipolar neurons were observed to contact the pineal lumen, which is continuous with the third ventricle, via dendritic processes of various types. It could not be established whether any of these CSF-contacting processes were identical with photoreceptor outer segments. The basal processes of the bipolar neurons sometimes possessed distally projecting collaterals. In conclusion, it has been shown that (i) different types of neurons displaying varied patterns of regional distribution contribute to the pineal tract, and (ii) certain CSF-contacting neurons in the pineal organ send axonal processes directly toward the brain.


External organisations
  • Justus Liebig University Giessen
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Neurosciences


  • Horseradish peroxidase technique, In-vitro studies, Neuronal projections, Neuronal types, Pineal organ, Teleostei
Original languageEnglish
Pages (from-to)693-700
Number of pages8
JournalCell and Tissue Research
Issue number3
Publication statusPublished - 1985 Jun 1
Publication categoryResearch