Fig. 4. Increased apoptosis in the vnd mutant pNE. (A,B) Anti-Caspase 3 antibody staining in the head ectoderm at late stage 11 (lst11); blue staining along the midline in A indicates the blue balancer. (A) In heterozygotes (wild type; wt) a few scattered apoptotic cells are observed in the pNE. (B) In vnd mutants (vnd-), apoptotic cells are significantly more abundant in the pNE, especially in the ventral part (broken white line), and are also more frequent in the ventral neuroectoderm of the mandibular (MD), maxillary (MX) and labial (LA) segment. (C-E) NB layer in the DC of vnd embryos. A corresponding region is framed by a broken black line in B. (C) Mid-stage 11 (mst11); Caspase-3 is detected in a few ventral deutocerebral NBs (black asterisks). (D,E) Slightly later (lst11), degenerating ventral NBs can be identified at corresponding positions by morphological criteria [e.g. condensation and fragmentation of the nucleus and cytoplasm; Abrams et al. (Abrams et al., 1993)]. (D) Svp-lacZ/En staining suggests that NBs in position of Dv4/5 and Dv7 undergo apoptosis. (E) Ems/En labeling reveals that the degenerating NB (presumably Dv7) ectopically expresses Ems (compare with Fig. 5B). as, en antennal stripe; CL, clypeolabrum.