An ultrastructural overview of podocytes and the glomerular endothelium. (A) Scanning electron micrograph of an exposed glomerulus. In this image, the Bowman’s capsule is broken, permitting a striking view of podocytes (Pod) completely wrapped around the glomerular capillaries. (B) Higher magnification of a podocyte within the glomerulus revealing the interdigitated FPs. (C) A resin cast of the glomerular capillary tuft with the cells corroded to reveal its highly convoluted shape. Image courtesy of F. Hossler (East Tennessee State University, Johnson City, TN). (D) Scanning electron micrograph of an exposed glomerular capillary and its numerous perforations (fenestrae). (E) Simplified diagram of the GFB. The GEC and its fenestrae are lined by a filamentous glycocalyx enriched in negatively charged proteoglycans. The glycocalyx and adsorbed plasma components form the thicker ESL. The GBM is a stratified ECM in between podocytes and GECs. Podocytes form the final layer of the GFB. The interdigitating FPs of podocytes are linked by porous SDs where primary urinary filtrate passes through. Bars: (A) 20 µm; (B and D) 1 µm; (C) 50 µm.