When does 6the embryo now has 3 germ layers ectoderm mesoderm endoderm?

The embryo develops three germ layers—ectoderm, mesoderm, and endoderm—during a process called gastrulation, which typically occurs around the third week of embryonic development, approximately 14-21 days after fertilization. These germ layers give rise to all the tissues and organs in the body: the ectoderm forms the skin and nervous system, the mesoderm develops into muscles, bones, and the circulatory system, and the endoderm forms internal structures such as the digestive and respiratory systems.