Compartmentation of the rabbit cerebellar cortex.

The cytoarchitecture of the adult rabbit cerebellum is revealed by using zebrin II/aldolase c immunocytochemistry in both wholemount and sectioned material. Zebrin II is expressed by approximately half of the Purkinje cells of the cerebellar cortex. In most regions these form a symmetrical array of zebrin II positive and negative parasagittal bands. Four transverse expression domains are identified in the vermis: (1) an anterior zone, comprising four narrow bands, one at the midline and three laterally to either side, extending throughout the anterior lobe to the primary fissure; (2) a central zone with broad immunoreactive bands separated by narrow zebrin II negative bands that disappear caudally to leave no apparent compartmentation; (3) a posterior zone with prominent alternating zebrin II positive and negative bands; and (4) a nodular zone in which all Purkinje cells express zebrin II. In the hemispheres a striped topography is found in lobules HVI, HVII, and crus I, and all Purkinje cells are zebrin II+ in the flocculus and paraflocculus. Because of its importance for the classical conditioning of the eyeblink response, we made a detailed analysis of lobule HVI of the hemisphere. The immunocytochemical data show a complex substructure within HVI with three prominent zebrin II positive bands (probably homologous with P4a+, P4b+, and P5+ of rodents) separated by two zebrin II negative regions (P4- and P4b-). Thus, the organization of the rabbit cerebellum is consistent with the patterns described previously for rat, mouse, and opossum and suggests that there may be a common ground plan for the mammalian cerebellum.