Fig. 4.

Amputation-induced apoptosis is stem cell-independent. Control and neoblast-ablated (irradiated) animals (Materials and methods) were amputated as described in Figure 1 and Figure 2. (A) Representative TUNEL patterns in head fragments (left) or pharynges isolated from regenerating trunk fragments (right). Head fragments were fixed at 4 hours or 3 days post-amputation. All pharynges were isolated and fixed at 3 days post-amputation. Scale bars = 100 µm. (B) Average TUNEL levels for 3 independent experiments (n ≥ 17 for each condition). Values for the 4-hour timepoint are restricted to the area within 100 µm of the amputation site (boxed areas in schematic diagrams). Error bars = +/− s.e.m. p values for two-tailed Student’s t-Tests comparing paired control and irradiated regenerating animals were all > 0.05, except for prepharyngeal anterior fragments. p values for comparisons of regenerating animals with their respective intact controls (or Group 1 vs. Group 2 for isolated pharynges) were all < 1 × 10⁻³.