In situ hybridization on retinal, brain and spinal cord sections for vim (A–C), des (D–F), prph (G–I), ina (J–L), and nes (M–O). Sections were obtained from pre-metamorphic stage 50 tadpoles. Location of the lens (L), outer (O), inner (I) and ganglion (G) cell layers are indicated. Scale bars, 100 μm in A, D, G, J and M; all others are 50 μm.