3340. The Eye Development in Vertebrates (Frog). . 10 Color Photomicrographs. 1. Early neurula, t.s. two pigmented grooves 2. Medium neurula, t.s. later stage 3. Later neurula, t.s. optic vesicles 4. Ditto. growing optic vesicles 5. Tail bud stage, t.s. f