Figure 5.
Parietal cells deposit matrix onto the GBM. Human biopsies of patients diagnosed with FSGS were costained for BC-type matrix or the GBM [(A and C) collagenIValpha3; or (B) agrin]. (A) CollagenIValpha3 was specifically detected within the capillary convolute (black arrowheads). An early lesion (white arrow) is in direct continuation with the BC-type matrix of Bowman's capsule (white arrowheads). (A‴) Higher magnification shows that BC-type matrix is deposited on top of the GBM. (B) The same results are obtained in early sclerotic lesions when staining for agrin, which stains the GBM (black arrowheads) as well as Bowman's capsule (black arrow). (C) Advanced sclerotic lesion, where most of the glomerular tuft is covered by BC-type matrix (white arrowheads). Within the endocapillary compartment, no BC-type matrix is deposited (black arrowhead). At the site of the adhesion, BC-type matrix is in continuity from Bowman's capsule onto the capillary convolute (white arrows) while no additional GBM is formed at this site.