The Purkinje cell class may extend beyond the cerebellum.

The cerebellum develops from a germinal zone at the rhombic lip of the metencephalon. This region, like the telencephalic vesicle which gives rise to the cerebral cortex, presumably consists of germinative units showing a rather repetitive neurogenetic pattern. In all cerebellar folia, cortical neurons, and especially the Purkinje cells, express highly stereotyped phenotypes, although some variations in their chemical make-up have been uncovered with monoclonal antibodies. Here, we demonstrate for the first time that three independent murine mutations, Lurcher, Purkinje cell degeneration and staggerer, which result in the postnatal degeneration of Purkinje cells, also cause the elimination of cartwheel cells of the dorsal cochlear nucleus. The cerebellar granule cell mutation, weaver, which spares most Purkinje cells in the lateral cerebellum, also spares cartwheel cells. These data support the notion that the cerebellar germinative zone extends to the caudal portion of the rhombic lip, which gives rise to the dorsal cochlear nucleus.