Figure 3. Effects of IR and MEC exposure on cellular senesecence in mouse intervetebral discs.
A, immunohistochemical detection of p16INK4a, a senescence marker, to distinguish senescent (brown, arrow) from non-senescent (blue) cells. B, Quantitation of the percent p16INK4a immunopositive cells in the nucleus pulposus of unexposed mice (C) and mice exposed to mechlorethamine (MEC) or ionizing radiation (IR). Top graph, Wt mice. Bottom graph, Ercc1−/Δ mice. * = p < 0.05 from nine random fields.