Get access

Anatomy of the posterior caudal lobe of the cerebellum and the eminentia granularis posterior in a mormyrid fish

Authors

  • Holly R. Campbell,

    1. Neurological Sciences Institute, Oregon Health and Sciences University, Beaverton, Oregon 97006
    Current affiliation:
    1. Department of Defense, Congressionally Directed Medical Research Programs, 1077 Patchel St., Fort Detrick, MD 21702
    Search for more papers by this author
  • Johannes Meek,

    1. Department of Experimental Animal Physiology, University of Nijmegen, 6526 ED, Nijmegen, The Netherlands
    Search for more papers by this author
  • Jianmei Zhang,

    1. Neurological Sciences Institute, Oregon Health and Sciences University, Beaverton, Oregon 97006
    Search for more papers by this author
  • Curtis C. Bell

    Corresponding author
    1. Neurological Sciences Institute, Oregon Health and Sciences University, Beaverton, Oregon 97006
    • Neurological Sciences Institute, Oregon Health & Science University, 505 N.W. 185th Ave., Beaverton, OR 97005
    Search for more papers by this author

Abstract

The cerebellum of mormyrid fish is of interest for its large size and unusual histology. The mormyrid cerebellum, as in all ray-finned fishes, has three subdivisions—valvula, corpus, and caudal lobe. The structures of the mormyrid valvula and corpus have been examined previously, but the structure of the mormyrid caudal lobe has not been studied. The mormyrid caudal lobe includes a posterior caudal lobe associated with the electrosense and an anterior caudal lobe associated with lateral line and eighth nerve senses. In this article we describe cellular elements of the posterior caudal lobe and of the eminentia granularis posterior (EGp) in the mormyrid fish Gnathonemus petersii. The EGp gives rise to the parallel fibers of the posterior caudal lobe. We used intracellular injection of biocytin, extracellular injection of biotinylated dextran amine, and immunohistochemistry with antibodies to gamma-aminobutyric acid, inositol triphosphate receptor I, calretinin, and Zebrin II. The histological structure of the posterior caudal lobe is markedly irregular in comparison to that of the corpus and the valvula, and a tight modular organization of cerebellar elements is less apparent here. Most Purkinje cell bodies are in the middle of the molecular region. Their dendrites are only roughly oriented in the sagittal plane, extend both ventrally and dorsally, and branch irregularly. Climbing fibers terminate only on smooth dendrites near the soma. Most Purkinje cell axons terminate locally on eurydendroid cells that project outside the cortex. The results provide an additional variant to the already large set of different cerebellar and cerebellum-like structures. J. Comp. Neurol. 502:714–735, 2007. © 2007 Wiley-Liss, Inc.

Ancillary