Fig. 5

Schematic drawing of combined head gap gene expression (upper panel) in comparison with the dynamics of hh1 expression (lower panel). The boundary between embryo rudiment and dorsal field, marked by a dashed line, is a gradual transition at the early stages, but becomes more defined during later development (compare Fig. 1). df = dorsal field (putatively ‘extra-embryonic’, characterised by lower cell density than the ventral part where the embryo forms) oc = ocular domain, ant/int = combined antennal and intercalary domain, ant = antennal domain, int = intercalary domain. Black arrows in b indicate split between the early otx-B and SP5 domains, red arrows in b and c indicate splits of the hh domain