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. Author manuscript; available in PMC: 2011 Dec 15.
Published in final edited form as: Dev Biol. 2010 Sep 26;348(2):231–243. doi: 10.1016/j.ydbio.2010.09.014

Figure 1. Induction of oenoyctes and secondary ch organ SOP cells by EGF signaling.

Figure 1

(A–C) Diagram of a typical abdominal segment (A1–A7) showing the development of the C1-C5 primary (1°) SOP cells, the secondary (2°) SOP cells, and the oenocytes. Dorsal is at top and the Spalt expression domain is shown in pink. (A) First, a set of 1° ch organ SOP cells are specified by ato during early embryogenesis (late stage 10/early stage 11). (B) Shortly after specification, the abdominal 1° SOP cells up-regulate rho and secrete the Spitz (Spi) EGF ligand. The relative expression levels of rho are denoted in green with the dorsal-most SOP cell (C1) expressing the highest amount of rho. (C) The activation of EGF signaling in neighboring cells induces a cluster of oenocytes (Oe, red) within the Spalt expression domain and three 2° ch organ SOP cells ventral to Spalt expression. (D) Close-up schematic of a stage 16 thoracic and abdominal segment comparing ch organ development and oenocyte formation within the dorsal/lateral ectoderm. Note, the T2/T3 thoracic segments contain three 1° SOPs (C1–C3) that form a dorsal ch organ consisting of three scolopodia (dch3). In contrast, the abdominal segments recruit two 2° SOPs to form a lateral ch organ with five scolopodia (lch5) as well as an lch1 organ (derived from the C4 SOP in A–C). In addition, only the abdominal segments recruit oenocytes that form in clusters in close proximity to the lch5 organ. For simplicity, only the neurons of each scolopodia are shown and the C5 neuron and other 2° scolopodia that form the ventral ch organs (VchA and VchB) are not shown. (E) Lateral view of a stage 16 Drosophila embryo immunostained using the mAb21A6 antibody (blue) that marks the scolopodial sensory cilia and a general nuclear neuronal marker (Elav, red). (E’-E”) Close-up view of the T3 thoracic and A1 abdominal segments highlighting the dch3 and lch5 scolopodial sensory cilia. (F) Close-up view of the T3 thoracic and A1 abdominal segment of a stage 16 Drosophila embryo immunostained using mAb21A6 (blue) and a HNF4 antibody (red) that marks oenocytes. Note that oenocytes only form within the abdominal segments.