Abnormal synaptic organization between granule cells and Purkinje cells in the new ataxic mutant mouse, pogo.

The pogo mouse is a new ataxic mutant derived from the Korean wild mouse. The pathological manifestations include difficulty in maintaining normal posture and the inability to walk straight. The ataxia becomes apparent at about 2 weeks of age. Electron microscopic studies of the pogo/pogo homozygous cerebellum, revealed that the ectopic spines emanating from the primary dendrite of Purkinje cells were observed. Major difference between pogo/pogo homozygous and non-affected pogo/+ heterozygous was the synaptic organization of the molecular layer. Parallel fiber varicosities were larger than normal and a single fiber often established synaptic contacts with up to four dendritic spines of a Purkinje cell. This correlation between the presence of altered synaptic organization in the cerebellum and ataxia in pogo/pogo mutant mice warrants further investigation.