Figure 2.

Consequences of mesangial failures for podocytes shown in schematics. (A) Normal situation. The integrity of the mesangium is indicated by a checker pattern. Podocytes are shown in blue. Parietal epithelial cells are shown in violet. (B) A breakdown of mesangial cell-glomerular basement membrane connections is shown at two sites indicated by the disappearance of the checker pattern. The consequences with respect to capillary 1 consist of a lengthening of the corresponding mesangial axis followed by the prolapse of the capillary and the associated podocyte into the urinary orifice.^11,17 With respect to capillary 3, the consequences of a breakdown of mesangial cell-glomerular basement membrane connections consist of a bulging of the mesangium and an expansion of the capillary followed by the peripheral displacement of the associated podocytes, which form contacts to the parietal epithelium. Correspondingly, displacement of capillary 2 would be followed by a tip lesion²¹ of capillary 4 by a vascular pole–associated tuft adhesion.²¹