Get access

Morphology of the olivocerebellar projection of the chick: An axonal reconstruction study

Authors

  • Kazuma Sasamura,

    1. Department of Systems Neurophysiology, Graduate School and Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan
    Search for more papers by this author
  • Hiroko Ohki-Hamazaki,

    1. Division of Biology, College of Liberal Arts and Sciences, Kitasato University, Kanagawa, Japan
    Search for more papers by this author
  • Izumi Sugihara

    Corresponding author
    • Department of Systems Neurophysiology, Graduate School and Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan
    Search for more papers by this author

Correspondence to: Izumi Sugihara, M.D., Ph.D., Dept. of Systems Neurophysiology, Tokyo Medical and Dental University Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan. E-mail: isugihara.phy1@tmd.ac.jp

ABSTRACT

The projection pattern of the olivocerebellar (OC) axons, which terminate mainly as climbing fibers (CFs) in the cerebellar cortex, tightly reflects the compartmental and developmental organization of the cerebellum as revealed by mapping and reconstruction studies in the rat. The avian cerebellum is well lobulated and longitudinally compartmentalized like the mammalian cerebellum. However, the projection pattern of the OC axons has not been studied in detail for most areas of the avian cerebellum. In the present study, we reconstructed labeled chick OC axons resulting from a small focal injection of biotinylated dextran amine into the inferior olive to investigate their morphological characteristics, and to determine their relationship to the general morphology of the chick cerebellum. Labeled CFs were distributed basically in a single longitudinally elongated narrow band-shaped area in lobules I–VIII, but in multiple, transversely widened, band-shaped areas in lobules IX–X. Three of the four reconstructed OC axons terminated in a single longitudinally band-shaped area in lobules IXa–c, whereas the other one terminated in multiple mediolaterally separated areas in lobule IXc, which is part of the flocculus. Single OC axons branched into 14 CFs on average. Two CFs occasionally merged to form a single terminal arbor. Axons also had thin, non-CF collaterals that projected either to a cerebellar nucleus or to the cortex. The results indicate that the morphological characteristics of OC axons, including branching and termination, are basically conserved between the chick and the rat. J. Comp. Neurol. 521:3321–3339, 2013. © 2013 Wiley Periodicals, Inc.

Get access to the full text of this article

Ancillary