Axon terminals labeled with antibody to synaptophysin in a normal control subject. Each panel represents a different Z-axis depth, in microns, below the tissue surface (indicated by the adjacent numbers). It can be seen that a zone of robust, uniform labeling of punctae is present between 1.5 and 2.5 uM of tissue depth. A higher power example of a labeled terminal, from the box in the 2.0 uM panel, is shown at lower right.