Fig. 5.

Ultrastructure of brainstem synapses from single or combined mutants. Comparison of the morphology of synapses in brainstem ultrathin sections from newborn mice revealed no obvious changes in the ultrastructure of the nerve terminals in mutant compared to wt mice. Shown are electron micrographs of representative active zones obtained from wt (A), APLP2^−/−/APP^−/−(B), and APLP2^−/−/APLP1^−/−(C) samples processed as described in Materials and Methods. At the presynaptic site mutants and control mice showed comparably sized vesicle clouds, including docked vesicles in close proximity to the membrane. Electron dense postsynaptic specializations were clearly detectable in both double mutants.