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Keywords:

  • Afrotheria;
  • lissiform cerebellum;
  • Purkinje cell;
  • whole mount immunohistochemistry;
  • zonal organization

Abstract

The mammalian cerebellum is histologically uniform. However, underlying the simple laminar architecture is a complex arrangement of parasagittal stripes and transverse zones that can be revealed by the expression of zebrin II/aldolase C. The cerebellar cortex of rodents, for example, is organized into four transverse zones: anterior, central, posterior and nodular. Within the anterior and posterior zones, parasagittal stripes of Purkinje cells expressing zebrin II alternate with those that do not. Zonal boundaries appear to be independent of cerebellar lobulation. To explore this model further, and to broaden our understanding of the evolution of cerebellar patterning, zebrin II expression has been studied in the cerebellum of the Madagascan hedgehog tenrec (Echinops telfairi), a basal insectivore with a lissiform cerebellum with only five lobules. Zebrin II expression in the tenrec reveals an array of four transverse zones as in rodents, two with homogeneous zebrin II expression, two further subdivided into stripes, that closely resembles the expression pattern described in other mammals. We conclude that a zone-and-stripe organization may be a common feature of the mammalian cerebellar vermis and hemispheres, and that zonal boundaries and cerebellar lobules and fissures form independently.