(A, C, E) No macro-cytoophidium formation can be detected in y w embryos at stage 1 (A), 12 (C) and 15 (E). (B, D, F) Overexpressing CTPsyn isoform C induces macro-cytoophidia in embryos at stage 1 (B), 12 (D), and 15 (F). Segments in embryos are labeled by a transcription factor Engrailed (red). IsoC, isoform C. Scale bars, 20 µm.