Fig. 5. Cell death in the neurectoderm of EGFR loss-of-function embryos. (A) SEM of head of stage 11 Egfr^f5 mutant, dorsal view, anterior to the left. Note domains of cell death in anterior head (pa) and posterior head (pc). The posterior domain covers the optic placode. (B) In stage-14 Egfr^f5 mutant the brain (br) is exposed and only a small rudiment of optic placode is left (olp; labeled with anti-FasII; compare to Fig. 3C). (C,D) SEM of stage-11 embryos, ventral view, showing cell death in ventral neurectoderm of Egfr^f5 mutant embryos. Cell death, indicated by light, round cell fragments (arrows in D), occurs scattered throughout ventral neurectoderm of stage 10/11 embryo. (E) Wild-type neurectoderm for comparison. (F,G) Comparison of EGFR activation with ‘pre-apoptotic domains’ in dorsal head of stage 10 embryo. (F) Domains of EGFR activation are visualized by anti-dpERK antibody (black staining), embryo is also labeled with Anti-phosphohistone H3 (brown staining). (G) Pre-apoptotic domains are labeled by probe against reaper. Note presence of anterior and posterior band of labeling (pa, pc). Other abbreviations: cf, cephalic furrow; ml, midline; tp, tracheal pit.