APP staining in the spinal cord of human ALS autopsies. Representative (case No. 12 see table 1 for details) degenerating human motor neuron with enlarged APP-positive vesicles in the cell soma. For comparison, a morphologically normal spinal cord motor neuron from the same autopsy is shown above (arrow). (A), a single plane image, (B) and (C), maximum projections from a stack of images obtained from confocal optical sectioning. (A), low magnification of MND spinal cord section stained with anti-APP. (B), high power magnification of the normal MN shown in (A), as a xy- (middle), yz- (left) and xz- (top) scan with diffuse staining of APP in the cell soma; (C), high power magnification of the degenerating MN shown in A, as an xy- (middle), yz- (left) and xz- (top) scan with enlarged vesicles, some of them larger than 2 μm (see crossing point of the planes in C with a vesicle diameter of 2.8 μm. The yz- and xz-scans reveal the three-dimensional APP-positive vesicles in the degenerating human motor neuron. Scale bar in (A), 50 μm.