Apoptosis is elevated in 2 week <i>ColX</i><sup><i>N617K</i></sup> and <i>C/X</i> growth plate cartilage.

<p><i>(A)</i> Representative 2 week wildtype (<i>Wt</i>), <i>Xbp1</i><sup><i>CartΔEx2</i></sup>, <i>ColX</i><sup><i>N617K</i></sup> and <i>C/X</i> tibial growth plate sagittal cryosections analysed by TUNEL with DAPI counterstaining; HZ—hypertrophic zone. Boxes inset indicate magnified areas of the hypertrophic zones containing TUNEL-positive chondrocytes. <i>(B)</i> TUNEL analysis of at least 6 tibial growth plate sections from each of 3 <i>Wt</i>, <i>Xbp1</i><sup><i>CartΔEx2</i></sup>, <i>ColX</i><sup><i>N617K</i></sup>, and <i>C/X</i> mice, expressed as the number of TUNEL-positive chondrocytes in the hypertrophic zone as a percentage of the total number of chondrocytes per zone (as defined by DAPI-stained nuclei), and showing standard deviation around the mean. <i>(C</i>,<i>D)</i> Representative 2 week <i>(C) ColX</i><sup><i>N617K</i></sup> and <i>(D) C/X</i> tibial growth plate cryosections, showing the distribution of TUNEL-positive cells along the antero-posterior axis of <i>ColX</i><sup><i>N617K</i></sup> and <i>C/X</i> hypertrophic zones, as demarcated by 10 consecutive columns (1–10) of arbitrary width. Plots depict the number of TUNEL-positive chondrocytes in each column as a percentage of the total number of chondrocytes per column (as defined by DAPI-stained nuclei), from the same <i>ColX</i><sup><i>N617K</i></sup> and <i>C/X</i> mice as analysed in <i>(B)</i>, and showing standard deviation around the mean. Statistical analysis performed using Student’s t-test, ** <i>p</i> < 0.01, *** <i>p</i> < 0.001.</p>