Figure 3. Parietal epithelial cell (PEC) activation was highest in aged FSGS mice. PECs were identified by PAX8 staining (green color, nuclear), and the subset of PECs undergoing activation were identified by CD44 staining (red color, cytoplasmic). (A-C) Quantitation of the percentage of PECs that are activated. (A) In outer cortical (OC) glomeruli, the percentage of PECs that were activated (PAX8+CD44+) along Bowman’s capsule (BC) was higher in aged mice at baseline and in FSGS. (B) In juxta-medullary (JM) glomeruli, the percentage of activated PECs were similar at baseline, but higher in aged FSGS mice compared to young FSGS mice. (C) When OC and JM glomeruli were combined, aged FSGS mice had the highest percentage of PECs that were activated. (D-G) Representative images of Pax8 and CD44 staining on BC. Images taken at 400x by confocal microscopy for PAX8 (green, nuclear), CD44 (red, cytoplasmic) and DAPI (blue, nuclear) staining. (D’-G’) Higher magnification of the white square shown above. Solid arrow shows examples of PAX8 staining; dashed arrow shows examples of CD44 below (D’-G’). As shown in the above graphs, the percentage of PECs along Bowman’s capsule that are activated was higher in aged baseline mice, and increased further at D28 of FSGS in aged mice.