Fig. 4. Delayed and asynchronous chondrocyte differentiation within Pten^Co/Co;Col2a1-Cre growth plates. (A,B) Long-term BrdU labeling-chasing assay. BrdU was retained in the nuclei of resting chondrocytes and of the cells within the neoplastic core after a 7-day chase in both control (A) and mutant (B) growth plates. (C,D) Short-term BrdU labeling-chasing assay. Hypertrophic chondrocytes that transited from proliferating chondrocytes were labeled after a 1.5-day chase. (E) Statistical analysis of the quantities of BrdU-positive hypertrophic chondrocytes in the femur and tibia. Mean ±s.d. of six sections from two mice of each genotype. ^**P<0.01. (F-M) Sections from P5 control (F,H,J,L) or mutant (G,I,K,M) femoral growth plate were hybridized in situ with RNA probes for Ppr (F,G), Ihh (H,I) or Col10a1 (J,K), or subjected to von-Kossa staining (L,M). Red bars indicate layers of terminal hypertrophic chondrocytes. Scale bar: 400 µm in A,B; 275 µm in C,D,J,K; 544 µm in F-I; 222 µm in L,M.