Degeneration of the Eyes of Tyrosine-Deficient Chick Embryos

Abstract
Subjecting 4-day-old chick embryos to a yolk-sac perfusion medium lacking tyrosine resulted in arrest of retinal pigmentation and in degeneration of the neural retina. Phenylaldnine was ineffective in replacing tyrosine. Possibly retinal tyrosinase played a part in initiating the degenerative changes.