Fig. 6. Defective G1 progression in 10-null proliferative chondrocytes. Reduction of BrdU-labelled (A) and cyclin-D-positive (B) nuclei of mutant proliferative chondrocytes in newborn (NB) mice and in mice at 2 weeks (2w) and 4 weeks (4w) of age. Bars represent mean±s.d. *P<0.05 compared to numbers in relevant control mice. Five sections from eight to twelve animals (A) and three animals (B) were analyzed per genotype. (C) Immunohistochemistry at the newborn stage reveals elevated expression of p16 and increased nuclear translocation of Stat1 and Stat5a in the proliferative zone of mutant growth plates compared to that in the wild type (n=3 animals per genotype and n=5 sections per animal). (D) In situ hybridization shows comparable expression levels of Fgfr3 in femurs from wild-type and mutant mice at E15.5. Bar, 100 µm.