Fig. 3. NMJ-capping cells are positive for CD34 antibody and CTB and reside outside the synaptic basal lamina. (A,B) Confocal projections of an NMJ-capping cell in a mouse triangularis sterni muscle immunostained with 2166 (green) and CD34 (red) antibodies and with endplate AChR counterstained (blue). Lower panels in A show green and red channels separately; Panels 1 and 2 in B show orthogonal projections at the optical cuts indicated in the uppermost panel. (C) Transverse section of a mouse TS muscle immunostained with 2166 antibody (green spots), laminin antibody (red) and endplate ACh receptor (blue). The immunostained processes of the NMJ-capping cells clearly lie outside the basal lamina. (D) Fluorescent conjugates of CTB also stain cells similar in form and location to NMJ-capping cells. Right panel shows the red channel indicating endplate ACh receptors only. Scale bars: 50 µm.