Localization of transcription factor Sal in presumptive nymphalid eyespot organizers. Immunostainings of Sal protein in last-instar larval wings of Nymphalinae and Satyrinae species with the corresponding adult wing (left) and sample size (bottom right corner). Sal expression in presumptive eyespot centers starts after tracheal expansion into the vein lacunae (corresponding to stages 0.75-1.25 cf. ). The individual wings shown here are developmental stage ~2. White arrows provide reference for the location of presumptive organizers of eyespot development. When expression is absent in forewings, it is also undetected on the hindwings.
Shirai et al. BMC Evolutionary Biology 2012 12:21 doi:10.1186/1471-2148-12-21