Electron micrographs of diaphragm neuromuscular junctions following injection with McAb-3 mAb. (a) Junction typical of those observed in Daf1+/+ animals. It appears completely normal with entirely normal synaptic architecture. ×25,000. (b) Junction from a Daf1–/– mouse that was obviously weak, shows reduced synaptic folds and a widened synaptic cleft. ×25,000. (c) Three neuromuscular junctions from Daf1–/– mice, all exhibiting simplified junctional folds. ×8,000. The electron-dense material seen in the synaptic clefts of the junctions in b and c is likely postsynaptic membrane shed from the muscle by complement-mediated destruction. This material is seen in (d) at a magnification of ×20,000.