Fig. 9. Absence of rapsyn at synaptic sites in E15.5, but not E18.5, ^-/- muscles. Diaphragm muscle sections at E15.5 (A-F) and E18.5 (G-L) from wild-type (A-C,G-I) and ^-/- embryos (D-F,J-L) were triple-labeled with anti-Syt2 (A,D,G,J), -bgt (B,E,H,K) and anti-rapsyn (C,F,I,L). At E15.5, rapsyn was highly localized to synaptic sites in wild-type muscles (arrowhead, C), but absent from synaptic sites in ^-/- muscles (F). There were also no AChR clusters (E) at synaptic sites (arrowhead in D) in the E15.5 ^-/- muscle. At E18.5, however, rapsyn (arrowheads) was localized to synaptic sites in both wild-type (I) and ^-/- muscles (L). Scale bar: 10 µm.