UNC-18 expression is not altered inunc-4 and unc-37 mutants. A ventral view of the vulval area is shown. Anterior is to the left. Double antibody staining was performed with UNC-17 and UNC-18 antibodies. A, D, UNC-18 antibody (red) stains the axonal processes of the VCs in a diffuse pattern (arrow). B, E, UNC-17 (green) is detected in VC varicosities associated with vulval muscles (arrow). C, F,Merged images show overlapping UNC-17 and UNC-18 antibody staining (yellow). A–C, In wild type, the UNC-17 and UNC-18 antibodies colocalize to VC axonal projections. D–F, In unc-4 mutants, UNC-18 (D, F) but not UNC-17 (E, F) (arrow) is detectable in VC axonal processes. All images are stacked confocal sections and were merged in Photoshop (C, F). Scale bar,A–C,D–F, 10 μm.