PERIVASCULAR EXTERNAL GRANULE CELLS IN HEREDITARY CEREBELLAR VERMIS DEFEAT RAT - PATHOGENESIS OF CEREBELLAR CORTICAL DYSPLASIA

Hereditary cerebellar vermis defect rats (CVD), a new neurological mut ant, developed disorganized cerebellar cortical tissues. The postnatal development of the cerebellum in the CVD was examined histologically and immunohistochemically. A main pathological change in the CVD was a bnormal perivascular cell aggregations, beginning to be observed from postnatal day 5. Around postnatal day 14, perivascular cells increased in number and many of them showed vigorous bromodeoxyuridine incorpor ation activities, as seen in the normal external granule cells (EGCs). The perivascular cells and EGCs were strongly positive for low affini ty nerve growth factor receptor. These immunohistochemical results rev ealed that abnormal perivascular cells were heterotopic EGCs. The peri vascular cells led to dysplastic abnormalities of lamination and abnor mal cell positioning in the CVD. These findings indicate that abnormal perivascular aggregations of EGCs play an important role in the patho genesis for cerebellar cortical dysplasia of CVD.