In the "black box" of human development known as gastrulation, an embryo transforms from a hollow, spherical structure to a multilayered one. Human embryos are typically not cultured for longer than 14 days due to bioethical concerns, and gastrulation happens between 17 and 21 days after fer
Gastrulation is a "black box" of human development in which an embryo reorganises itself from a hollow spherical to a multilayered structure. Because of bioethical considerations, human embryos are normally not cultured for more than 14 days, and gastrulation occurs between 17 and 21 days po