Fast Red and Fast Blue permit chromogenic and fluorescent transcript visualization. Lateral views of embryonic brains at 24 hpf hybridized to nkx6.1 digoxigenin and/or pax6a dinitrophenol antisense RNA probes as indicated on each panel. Transcript distributions were visualized by chromogenic (A,C,E) or fluorescent (B,D) detection of Fast Blue (C,D,E) and Fast Red (A,B,E) precipitates as indicated. Embryos were viewed on an Axioplan II microscope and images were recorded with an Axiocam digital camera. Fluorescent signals were false-colored in ImageJ. Scale bar is 100 μm.