Figure 5. Confocal images of CST axon varicosity showing colocalization of BDA, PSD-95, and SYN. A, Axon terminal in the spinal intermediate zone from a control animal. A, Projection image (10 1-μm optical slices), triple labeled. A1–A3, One micrometer optical slice showing a BDA staining only (A1), PSD staining (A2), and SYN staining (A3). Yellow arrows point to labeling present; gray arrow point to the location in which optimal labeling for SYN (A3) and PSD (A5) is not present. A4–A6 are similar to A1–A3 but for the next optical slice. Insets in A1 and A4 show triple label for the single optical slices. B, Low-magnification view of location of CST label in the contralateral cervical spinal cord. Red box contains the axon used for analysis in C. C, Axon terminal in the spinal intermediate zone in a projection image; BDA staining only. The region outlined by the yellow square in C is shown in C1–C4, which are the same 1 μm optical slice but with different staining. The yellow arrow points to the same location in C1–C4. C1, Overlay of BDA, PSD-95, and SYN labels. C2, BDA only. C3, SYN only. The arrow points to a puncta of SYN. C4, PSD-95 only. The arrow points to a puncta of PSD-95. Scale bars, 10 μm.