Figure 3.

Distribution of mouse bladder Pdgfra/PDGFRA⁺ fibroblasts. A: expression of Pdgfra in the bladder wall of Pdgfra^H2B-EGFP reporter mice as revealed by confocal microscopy. Tissue was counterstained with phalloidin to reveal the actin cytoskeleton (white) and DAPI (blue) to reveal cell nuclei. Actin was associated with the cortical cytoskeleton of most cells but strongly labeled the actin filaments that abound in the cytoplasm of smooth muscle cells. As expected for a nucleus-localized reporter, the H2B-enhanced green fluorescent protein (EGFP) signal overlapped completely with the DAPI signal (see insets for example of the DAPI signal alone and EGFP signal alone). Representative confocal micrographs from two mice are shown. B: bladder tissue from Pdgfra^H2B-EGFP reporter mice was counterstained with antibodies to PDGFRA, CAR3, or CD34. Representative confocal micrographs from two mice are shown. Examples of H2B-EGFP⁺ nuclei that were also positive for PDGFRA, CAR3, or CD34 are marked with yellow arrows. In the top images, a small number of cells were found that were PDGFRA⁺ but H2B-EGFP^– (nuclei marked with orange arrows) or were H2B-EGFP⁺ but PDGFRA^– (nuclei labeled with cyan arrows). C: PDGFRA⁺ cells (green) were found in the following regions: the suburothelial region (SU); in the subjacent outer lamina propria (OLP), which forms the core of the rougae (Ru) and extends below suburothelial cells in the unfolded regions; within the perimysial connective tissue in the intermuscular region (IM); and in the serosa (Se), where a single layer of cells was sandwiched between the smooth muscle and mesothelial cell (MC) layer. The tissue was counterstained with DAPI (blue) and phalloidin (white; bottom images). The boxed regions in the top left images are magnified in the adjacent images. Representative confocal micrographs from four experiments (each with 2–3 mice) are shown.