The superior colliculus of the camel: A neuronal-specific nuclear protein (NeuN) and neuropeptide study

Eric P.K. Mensah-Brown, L. J. Garey

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


In this study we examined the superior colliculus of the midbrain of the one-humped (dromedary) camel, Camelus dromedarius, using Nissl staining and anti-neuronal-specific nuclear protein (NeuN) immunohistochemistry for total neuronal population as well as for the enkephalins, somatostatin (SOM) and substance P (SP). It was found that, unlike in most mammals, the superior colliculus is much larger than the inferior colliculus. The superior colliculus is concerned with visual reflexes and the co-ordination of head, neck and eye movements, which are certainly of importance to this animal with large eyes, head and neck, and apparently good vision. The basic neuronal architecture and lamination of the superior colliculus are similar to that in other mammals. However, we describe for the first time an unusually large content of neurons in the superior colliculus with strong immunoreactivity for met-enkephalin, an endogenous opioid. We classified the majority of these neurons as small (perimeters of 40-50 μm), and localized diffusely throughout the superficial grey and stratum opticum. In addition, large pyramidallike neurons with perimeters of 100 μm and above were present in the intermediate grey layer. Large unipolar cells were located immediately dorsal to the deep grey layer. By contrast, small neurons (perimeters of 40-50 μm) immunopositive to SOM and SP were located exclusively in the superficial grey layer. We propose that this system may be associated with a pain-inhibiting pathway that has been described from the periaqueductal grey matter, juxtaposing the deep layers of the superior colliculus, to the lower brainstem and spinal cord. Such pain inhibition could be important in relation to the camel's life in the harsh environment of its native deserts, often living in very high temperatures with no shade and a diet consisting largely of thorny branches.

Original languageEnglish
Pages (from-to)239-250
Number of pages12
JournalJournal of Anatomy
Issue number2
Publication statusPublished - Feb 2006


  • Dromedary
  • Enkephalin
  • Midbrain
  • Nociception
  • Periaqueductal grey

ASJC Scopus subject areas

  • Anatomy
  • Histology
  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Developmental Biology
  • Cell Biology


Dive into the research topics of 'The superior colliculus of the camel: A neuronal-specific nuclear protein (NeuN) and neuropeptide study'. Together they form a unique fingerprint.

Cite this