Figure 4. Activated PECs migrated from Bowman’s capsule to the glomerular tuft in FSGS. (A-C) Quantitation showing the percentage of glomeruli with activated PECs (PAX8+CD44+) on the glomerular tuft. Aged FSGS mice had the highest percentage of activated PECs on the tufts of outer cortical (OC) (A), juxta-medullary (B) and combined OC and JM (C) glomeruli. (D-G) Representative images of Pax8 and CD44 staining on tuft. Images of glomeruli (400x) taken by confocal microscopy, showing staining for PAX8 (PEC marker, green, solid arrows), CD44 (activation marker, red, dashed arrows) and DAPI (nuclei, blue). Glomeruli are marked by the dashed line. (D’-G’) Higher power images of the area demarcated by the solid square shown above. PAX8 staining was detected along Bowman’s capsule in young baseline (D, D’) and aged baseline (E, E’) mice, but not in the glomerular tuft. (F, F’) In young FSGS mice, activated PECs were not readily detected on glomerular tufts. (G, G’) Activated PECs were detected on the glomerular tuft of aged FSGS mice. These results show that activated PECs were detected on the tuft of a subset of aged FSGS glomeruli.