Fig. 7. TUNEL stain. Stage 12-15 embryos were assessed for apoptotic cell death. Canton-S control embryos (A) show background staining in the developing gut. Sply⁰⁵⁰⁹¹ homozygotes (B) consistently show an overall increase in TUNEL-positive cells with a notable cluster at the posterior tip (arrow). The frequency of appearance of this cluster was substantially reduced by both excision of the P-element (C) and by introduction of a single copy of lace^k05305 (D).