Fig. 1. Expression of Poxm protein in developing larval body wall muscles during embryogenesis. (A-L) Whole-mount wild-type embryos were stained with purified anti-Poxm antiserum. Entire embryos (A,C,E,G,I,K) and enlarged views of parasegments 6-8 (B,F,H), 7 and 8 (D), or 6-9 (J,L) at early stage 10 (A,B), late stage 10/early stage 11 (C,D), mid stage 11 (E,F), stage 12 (G,H), stage 13 (I,J) and stage 15 (K,L) are shown. Note that the characteristic triangular pattern of early Poxm expression (D) in parasegments 2-14 is obscured in the overviews (C,E) because not all Poxm-expressing cells are in focus. Therefore, embryos were unfolded and flattened to show enlarged views of parasegments at extended germ band stages (B,D,F) and during germ band retraction (H). Embryos are oriented with their anterior to the left and dorsal side up. At stage 12, Poxm is expressed in the founders of muscles DO3, DT1, VA1-3 and in the ventral adult precursor (VaP; H), and later in the precursors of these muscles except DO3 and VaP (J,L). (M-O) Muscles that express Poxm were identified by double-labeling of embryos from P{Mhc-tauGFP}/TM6B parents with anti-GFP and anti-Poxm to reveal the muscle pattern (M), the late Poxm expression (N) and the merged image (O). Lateral and ventral muscles in four abdominal hemisegments of a stage 15 embryo with its anterior to the left and dorsal side up are shown. Note that muscles VA1 and VA2 overlap dorsally. For muscle nomenclature, see Bate (Bate, 1993) or Fig. 4J,N.