Apoptosis <i>in situ</i>.

<p>Mice at the indicated ages were killed and apoptosis of insulin-expressing cells on islet sections was determined by the TUNEL assay. <b>A.</b> Examples of early and late apoptotic cells as well as apoptotic bodies (white arrowheads). The structure indicated by the red arrowhead is not considered as an apoptotic cell because it does not contain DNA (i.e. not stained with the Hoechst dye). Such structures are not included in the quantitation shown in panel B. <b>B.</b> Representative images of whole islet sections from 16 week-old animals stained for insulin and DNA and subjected to TUNEL. <b>C.</b> Quantitation of TUNEL-positive cells within the insulin-containing cell population. Results are derived from 5–6 mice per age group and genotype.