Fig. 8

CR expression in cells of embryonic connective tissue (mesenchyme) in mouse embryos of E14.5 and E16.5 (a, b). The developing lung mesothelial precursor cells surrounding the lung (epithelial) tissue show transient expression of CR. Cuboidal proliferative cells including a mitotic cell (* in D) show high CR expression, while likely differentiated mesothelial cells (flat morphology, arrowheads in c & d) show weak to absent CR immunoreactivity (c, d). Schematic drawing of the proposed differentiation process from precursor mesenchymal cells to mesothelial cells and the corresponding transient CR expression (e). The proposed model is in agreement with recent findings of lineage analysis during lung mesenchyme development [43]. Scale bar 50 μm in (a) and (c) and 100 μm in (b) and (d)