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. 2011 Oct 11;2:500. doi: 10.1038/ncomms1510

Figure 7. Schematic illustrations showing the changes in gene expressions involved in Achaearanea head segmentation.

Figure 7

The expression domains of At-hh (blue waves), At-otd (brown boxes), At-opa (green boxes), and At-Dfd (purple boxes) along the AP axis at five successive stages of development are illustrated. Only the head and thoracic regions are shown. The At-otd-positive wave of At-hh expression, marked by '0', is defined as the generative zone for the Pp and Ch segments, which form by stripe splitting in that order and are indicated by '1' and '2', respectively. The anterior margin of the forming germ band (closed triangles) and the At-hh expression stripe related to the L4 segment (asterisks) are also indicated. At-otd eRNAi inhibits At-hh expression in the head generative zone, and At-opa eRNAi prevents the At-otd-positive At-hh stripe from splitting. In earlier stages (late stage 5 and early stage 6), At-otd eRNAi inhibits the departure of the At-hh stripe from the rim of the germ disc, but this fact is not shown.