Photoreceptor development in premetamorphic and metamorphic Xenopus laevis

Transgenic Xenopus laevis are commonly used to study gene expression in photoreceptors, but only red rods and red cones are known to exist in the pre-metamorphic stages commonly used in transgenic studies. Using RT-PCR, this study shows that violet cones develop in early pre-metamorphic stages (Stage 35) with the red rods and red cones. Green rod development began in Stage 53 with the onset of metamorphosis.