Embryo of the dwarf cuttlefish, Sepia bandensis, stained with phalloidin (F-actin; green), DAPI (nuclei, blue), and anti Pax 3/7 (MAb DP312, red). The developing cuttlebone (purple) and eyes (yellow) were rendered using the DIC image collected during the confocal scan. The F-actin staining (green) reveals the developing musculature and brain, while Pax 3/7 (red) is expressed in a subset of neurons in the brain as well as two patches of epithelia in the mantle and portions of the arms and tentacles. The cuttlebone (purple) is a chambered, gas-filled internal shell made of aragonite that provides buoyancy control. Within each eye (yellow), the developing lens is seen as an internal sphere. Seven of the eight arms are visible along with the two tentacles that have sucker-covered ends.