On the architecture of the posterior zone of the cerebellum.

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 many molecules, in particular, zebrin II/aldolase C. By using a combination of Purkinje cell antigenic markers and afferent tracing, four transverse zones have been identified: in mouse, these are the anterior zone (∼lobules I-V), the central zone (∼lobules VI-VII), the posterior zone (PZ: ∼lobules VIII-dorsal IX), and the nodular zone (∼ventral lobule IX + lobule X). A fifth transverse zone-the lingular zone (∼lobule I)-is found in birds and bats. Within the anterior and posterior zones, parasagittal stripes of Purkinje cells expressing zebrin II alternate with those that do not. To explore this model further and to broaden our understanding of the evolution of cerebellar patterning, stripes in the PZ have been compared in multiple mammalian species. We conclude that a posterior zone with a conserved stripe organization is a common feature of the mammalian and avian cerebellar vermis and that zonal boundaries are independent of cerebellar lobulation.