The IPS in human glomeruli. A: Example SBF-SEM micrographs of the human glomerulus (Additional file 9: Movie S5A). B: The same micrograph as A but with capillaries (red) and urinary spaces (orange) highlighted and example podocytes (P) and white blood cell (W) labelled. The inter-podocyte space (IPS) and periphery urinary spaces (PUS) are shown (Additional file 10: Movie S5B). C: The extracted IPS as a volume at different angles. The circle is the IPS marked by the circle in B. The arrows and highlights in C-0 and C-60 point to the two connections with larger IPS. The arrow in C-0 is a substantial connection (circa 5 μm wide, though this channel is filled with podocyte cell bodies), but the connection between this IPS and the circled IPS is a narrow (<1.5 μm) neck (label: N in C-120) and is tortuous with podocyte parts occluding the channel. The other connection to the circled IPS (arrow in C-60) is highly tortuous and very narrow channel if it connects at all. See Additional file (Additional file 11: Movie S5C) for the whole image and reconstruction. Scale Bars = 10 μm.