Figure 2. Widespread synaptic degeneration in the striatum of young (2 month old) wild-type, but not heterozygous Wld^S or homozygous Wld^S mice, 3 days after cortical lesion.

Representative electron micrographs of striatal synapses at low power (A) and higher power (B) from a young wild-type mouse (top panel), heterozygous Wld^S mouse (middle panel) and homozygous Wld^S mouse (bottom panel). Asterisks indicate degenerating synaptic profiles (identified principally by their electron dense cytoplasm) and arrows indicate healthy (i.e. non-degenerating) synaptic profiles. Degenerating synapses were readily identified in wild-type mice, occasionally observed in heterozygous Wld^S mice and rarely observed in homozygous Wld^S mice. However, the morphological appearance of degenerating synapses was indistinguishable between the different genotypes, suggesting that synapses in mice expressing the Wld^S gene ultimately degenerate by the same mechanism as in wild-type mice, albeit after a delay. Scale bars; A = 1 µm, B = 0.5 µm.