Actinomycin D: Specific Inhibitory Effects on the Explanted Chick Embryo

Abstract
Chick embryos containing 11 to 13 somites were cultured for 48 hours on media containing various amounts of the antibiotic actinomycin D. Morphological observations as well as quantitative determinations of protein nitrogen, DNA, and RNA indicate that the antibiotic specifically inhibits the growth and development of the embryonic axis posterior to the 12th somite.