AbstractFollowing the removal of polyethylene glycol (PEG) from thin sections, and viewing through the endothelial fenestrae and/or the interpedicel spaces, the rat renal glomerular basement membrane in situ was revealed to consist of meshworks and to be electron‐transparent when examined at right angles to the plane of the membrane. By subsequent platinum replication of the embedment‐free sections, the lamina densa of the basement membrane appeared as a veil composed of rather closely packed particles. The architecture of the slit diaphragm and the surface morphology of the endothelial cell membrane were also clearly revealed. The present results indicate that the PEG method, with or without replication, can provide valuable information on basement membrane morphol