Fig. 4

Expression of hh1 (a–g) and hh1 expression combined with otx-B (h). a, c–g ventral view. b lateral view. a (stage 2.2, early) First expression of hh1 appears. b (same specimen as a) The early hh1 domain covers about 50% of the egg circumference. c (stage 2.2, late) The 1st split of the early hh domain has begun laterally; this produces the ocular hh stripe. d (stage 2.2, late) The splitting-off of the ocular stripe has reached the medial domain. The mandibular stripe is faintly visible; it appears de novo, the lateral ends connecting to the initial, more anterior domain. e (stage 2.3, early) The ocular stripe has completely separated. The more posterior domain has begun to split into antennal and intercalary stripes. f (stage 2.3, early) Antennal and intercalary domains have split centrally but stay attached laterally. g (stage 2.3, early) First appearance of the 1st maxillary stripe. h/h′ (stage 2.2, late, showing the lateral part of the head domain). h otx-B channel only. h′ otx-B expression overlaps with the ocular hh stripe. Dashed line is in same place in h and h′ and marks the posterior limit of both the otx-B and the ocular hh domain. oc = ocular domain, ant/ic = antennal/intercalary domain