Fig. 7. Measurements of the height of the proliferating zones and of the distance between opposing growth plates during femur development. Each bone section was stained with anti-ColX antibody to distinguish the proliferating (ColX negative) from the hypertrophic (ColX positive) zone. Measurements of the height of the proliferative and hypertrophic zone were performed along the central axis of a longitudinal section of the growth plate. (A) Height of the proliferating zone; (B) distance between opposing growth plates measured from the inner borders of the collagen X positive hypertrophic zones. Values (±s.d.) represent the mean of measurements from four different sections performed using a measuring microscope eyepiece and are expressed in arbitrary units. Statistical analysis of the differences between wild-type (WT) and Stat1^-/- mice, or WT and TgFGF values, respectively, shows significant differences (P<0.01-0.001) for the values indicated with an asterisk.