Carnegie Stage

The Carnegie stages are a standardized way scientists classify early human embryos based on their physical development during the first eight weeks after fertilization. These stages, numbered 1 through 23, describe specific features like size, shape, and the formation of organs and body parts, allowing researchers to compare and understand embryonic development consistently. Named after the Carnegie Institution where the research was conducted, this system helps scientists track developmental milestones, study abnormalities, and compare human growth to other species in developmental biology.