HEREDITARY CEREBELLAR VERMIS DEFECT IN THE LEWIS RAT

We report a new rat model of hereditary cerebellar vermis defect. Muta nt rats exhibited hind-leg paralysis from about 14 days old. Gross pat hology showed the cerebellar vermis defect, fused cerebellar hemispher es and cyst formation. Ectopic dysplastic cerebellar tissues existed i n the cerebello-pontine junctional zones. Mild disarrangement of lamin ation was also observed in the fused cerebellar hemispheres. The prese nt mutant may serve as a valid model for studying the cerebellar vermi s defect under the genetic control.