Fig. 7. TUNEL labeling of the sling. Coronal cryostat sections at 10 µm were labeled using TUNEL and an FITC secondary antibody. TUNEL-positive cells were present within the sling at E17 and E18 (arrows in A and B respectively) but no TUNEL-positive cells were present at P0 (C) or P3 (D), despite the continuing generation of the sling cells at these ages (see Fig. 3). Even at P5 (E) and P10 (F) when the sling structure disappears there is no TUNEL labeling. Scale bar: 200 µm in all panels.