Morphogenesis of cerebellar lesions in bovine familial convulsions and ataxia.

Cerebellar lesions develop in a heritable disorder characterized by recurrent episodic seizures in newborn and young calves and by ataxia in survivors of several bouts of convulsions. Earliest changes were altered patterns of phosphatase reaction products in Purkinje cells. Purkinje cells axons in the outer half of the granular layer developed fusiform or spheroidal argyrophilic swellings. Early lesions were restricted to the lingula and uvula, but cases with more persistent clinical disease involved other parts of the vermis. In ataxic calves these lesions were also in the cerebellar hemispheres. The axonal swellings showed proliferation of tubulovesicular endoplasmic reticulum, neurofibrils and mitochondria. In other swellings axoplasm was degenerate, and in some it resembled Purkinje cell cytoplasm. In some clinically normal adult transmitters of the disorder, light microscopy showed some similar swellings, but most calves that recovered had no lesions.