Fig. 7. hb expression during abdomen formation. Grasshopper Hb and engrailed double immunolabeling allow localization of hb domains during abdominal growth. At 17%, the posterior boundary of the hb weak domain (black) extends to the T1 engrailed stripe (brown, A, closer view in B). As the gnathal engrailed stripes appear (C, closer view in D), the anterior Hb domain (black, bracket) can be seen to extend from the posterior of Mn to anterior T1 (brown lettering indicates position of engrailed stripes for the various segments – mandibular (Mn), maxillary (Mx), labial (La) and the first thoracic segment (T1)). By 22%, a broad abdominal stripe appears (bracket in E). This is posterior to the A1 engrailed stripe, and is followed at 24% (F, in situ hybridization for hb in L. migratoria) with the appearance of a second abdominal domain (arrow indicates A4/A5 domain, arrowhead indicates the newly appearing A7-A9 domain). This second abdominal domain is also evident at the protein level at 26% (bracket in G, closer view in H), but the A4/A5 domain has faded away. The appearance of the engrailed A7 stripe (black, I) at 27%, allows placement of the anterior boundary of the second Hb domain at posterior A7. Immunostaining in S. americana (A-E,G-I) and in situ hybridization in L. migratoria (F), reveal similar expression domains.