(a) PTHrPLacZ/+ mandibular first molars (M1) sections at P3 were stained for β-galactosidase activity and EdU, which was administered twice (6 and 3 h) prior to analysis. Right panel: a magnified view of the dotted area. Blue: LacZ, green: EdU-Alexa488. White arrowheads: LacZ−EdU+ dental papilla cells, white arrows: LacZ−EdU+ dental follicle cells, yellow arrows: LacZ+EdU+ dental follicle cells. Scale bars: 500 μm (left panel) and 100 μm (right panel). (b–d) PTHrPLacZ/+ M1 sections were stained for β-galactosidase activity at P7 (b), P14 (c) and P49 (d). Right panels: magnified views of the dotted areas counterstained with eosin. The inset of the right panel shows a further magnified view of the dotted area. Yellow and blue arrowheads: LacZ+ dental follicle cells at root formation front, immediately outside HERS (b) and on root surface (c,d). DP: dental papilla, DF: dental follicle. Scale bars: 500 μm (left panels), 50 μm (right panels) and 20 μm (inset). (e,f) P7 M1 sections were stained for nuclei, anti-PPR antibody (G220) (e) or its isotype control (sc-3888) (f), both at 5 μg ml−1. Yellow arrows: PPR+ odontoblasts, yellow arrowheads: PPR+ pericytes, yellow asterisks: PPR+ dental pulp cells, blue arrows: PPR+ dental follicle cells. Red: PPR-Alexa546, blue: DAPI. Scale bar: 200 μm.