Fig. 1. Segmental position of the Tc'Kr expression domain. Wild-type embryos stained for Tc'Kr (brown, A-G) and Tc'eve (blue, B-E). As in the remaining figures, all embryos are oriented anterior towards the left. The gap domain of Tc'Kr arises at the posterior pole of the blastoderm (A, posterior pit stage). In early germ rudiments (B,C) Tc'Kr expression extends from the 2nd Tc'eve stripe to beyond the 3rd Tc'eve stripe. When the 2nd (D) and 3rd (E) Tc'eve stripes split into segmental stripes 2a, 2b, 3a and 3b, the Tc'Kr gap domain (brown bar) is demarcated by 2a and 3b, i.e. it covers the three thoracic segments (E). At later stages, secondary expression domains arise in the head and eventually in all segments of the extended germ band (F,G). md mandible; T1 to T3, thoracic segments 1 to 3; A9, 9th abdominal segment.