Figure 4.

Bladder fibroblasts express Pdgfra. A and B: ultrathin cryosections obtained from Pdgfra^H2B-EGFP mouse bladders were immunogold labeled to reveal Pdgfra⁺ cells expressing the nucleus-localized H2B-enhanced green fluorescent protein (EGFP) marker. As cryo-electron microscopy (EM) generates relatively low-contrast images, we color coded the cytoplasm of the fibroblasts yellow and their nuclei blue. A: EM images of suburothelial fibroblasts. The dashed boxed regions in the top left image are magnified in their indicated images. Positive nuclei (Nu) contained gold particles. Collagen fibers (Col) were found in the matrix surrounding the cells. B: EM image of an intermuscular fibroblast closely apposed to smooth muscle cells (SMC), which are false colored green in the left micrograph. The dashed boxed region in the left image is magnified in the right image. Mitochondria (Mi) are marked. Data are representative of images acquired from two mice. Nuclei of nonfibroblast cells were negative, and control experiments performed in the absence of primary antibody also exhibited no staining.