Figure 6: Cells of the reserve zone are not recruited into the proliferative pool but undergo apoptosis in PPR cKO mice.

(a) Scheme showing BrdU labelling of reserve zone cells (stem-like chondrocytes) and EdU labelling of proliferating chondrocytes in the growth plate of control (PPR fl/fl) and PPR cKO (Col2-CreERt; PPR fl/fl) mice. (b) Sections from control and PPR cKO mice treated as shown in a were stained for both BrdU and EdU. Double BrdU- and EdU-labelled cells were not observed in PPR cKO mice. (c) Sections from control and PPR cKO mice treated as shown in a were stained for both BrdU and simultaneously for apoptosis (TUNEL). Increased number of double TUNEL+BrdU-positive cells (arrows) was observed in PPR cKO mice as compared with control mice. Scale bars, 100 μm.