Figure 10. Retina access is dependent on the embryonic stage. The diencephalic ventricles were injected at stage 24 (A, B) or stage 31 (C, D), and the embryos allowed to mature to swimming tadpoles. The eyes of both tadpoles appear to have developed normally. Cy3 fluorescence, which is appreciated through the pupil (arrow), is present only in the stage 24 injected tadpole. Such retinal labeling can be achieved through stage 29/30. For stages 31 and older, brain ventricle injection does not support delivery to the retina.