Interface between podocyte and endothelium in wild-type and Col4a3 mutant mice. (a) HIM images of the interface between podocytes and endothelium in WT, Col4a3+/−, and Col4a3−/− mice. The WT image shows well organized foot processes lining the capillary loops. A similar pattern is seen in Col4a3+/− mice. In Col4a3−/− mice, foot processes appear effaced and form flat sheets covering the GBM. “Bridging” process structures are detectable underneath the podocyte cell body. Scale bars, 500 nm. (b) Transverse image of the interface between podocytes and endothelium in Col4a3−/− kidney shows largely effaced foot processes and bridging process structures. The bridging processes and flattened podocyte cell body arched over effaced foot processes are indicated by a black arrow. The disappearance or fragmentation of the diaphragm-like structure underneath the fenestrae is indicated by a white arrow. Scale bar, 100 nm.