Hereditary cerebellar vermis defect in the Lewis rat.

We report a new rat model of hereditary cerebellar vermis defect. Mutant rats exhibited hind-leg paralysis from about 14 days old. Gross pathology showed the cerebellar vermis defect, fused cerebellar hemispheres and cyst formation. Ectopic dysplastic cerebellar tissues existed in the cerebello-pontine junctional zones. Mild disarrangement of lamination was also observed in the fused cerebellar hemispheres. The present mutant may serve as a valid model for studying the cerebellar vermis defect under the genetic control.