Co-expression of Tt-Pax6 and Tt - Otx in the apical lobe. (A) Dorsal view of Tt-Pax6 expression in the developing lobe of the early larva. (B) Dorsal view of Tt-Otx expression in the developing lobe of the early larva. (C-F) Double label in situ with Tt-Pax6 and Tt-Otx probes. All images are of the same embryo. (C) DIC image of double label in situ with Tt-Pax6 (red; Fast Red TR/Naphthol AS-MX) and Tt-Otx (blue; NBT/BCIP) probes, showing overlapping expression in two lateral stripes (black arrows). (D) Fluorescence image of Tt-Pax6 expression. (E) False color image of Tt-Otx expression, captured with brightfield illumination and a TRITC filter set to eliminate Fast Red TR/Naphthol AS-MX signal. (F) Merge of Tt-Pax6 and Tt-Otx, demonstrating overlap in two lateral stripes (white arrows).