Brain Structure and Function

, Volume 212, Issue 2, pp 209–221 | Cite as

Precerebellar and vestibular nuclei of the short-beaked echidna (Tachyglossus aculeatus)

  • K. W. S. AshwellEmail author
  • G. Paxinos
  • C. R. R. Watson
Original Article


The monotremes are a unique group of living mammals, which diverged from the line leading to placental mammals at least 125 million years ago. We have examined the organization of pontine, inferior olivary, lateral reticular and vestibular nuclei in the brainstem of the short-beaked echidna (Tachyglossus aculeatus) to determine if the cyto- and chemoarchitecture of these nuclei are similar to that in placental mammals and marsupials. We have used Nissl staining in conjunction with enzyme-histochemistry for acetylcholinesterase, cytochrome oxidase and NADPH diaphorase as well as immunohistochemistry for non-phosphorylated neurofilament protein (SMI-32 antibody) and calcium binding proteins (parvalbumin, calbindin, calretinin). Homologies could be established between the arch shaped inferior olivary complex of the echidna and the principal, dorsal and medial accessory subdivisions of the therian inferior olivary complex. The pontine nuclei of the echidna included basilar and reticulotegmental components with similar cyto- and chemarchitectural features to therians and there were magnocellular and subtrigeminal components of the lateral reticular nucleus, also as seen in therians. Subdivisions and chemoarchitecture of the vestibular complex of the echidna were both similar to that region in rodents. In all three precerebellar nuclear groups studied and in the vestibular nucleus organization, the cyto- and chemoarchitecture of the echidna was very similar to that seen in therian mammals and no “primitive” or “reptilian” features were evident.


Pontine nuclei Inferior olive Lateral reticular nucleus Vestibular nuclei Non-phosphorylated neurofilament protein Parvalbumin Calbindin Calretinin 



This work was supported in part by a grant from the Australian Research Council. We would like to thank Dr. Hong-qin Wang and Dr. Luan-ling Zhang for assistance in tissue processing.


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • K. W. S. Ashwell
    • 1
    Email author
  • G. Paxinos
    • 2
  • C. R. R. Watson
    • 3
  1. 1.Department of Anatomy, School of Medical SciencesThe University of New South WalesSydneyAustralia
  2. 2.Prince of Wales Medical Research InstituteThe University of New South WalesSydneyAustralia
  3. 3.Division of Health SciencesCurtin University of TechnologyBentleyAustralia

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