Ectoderm is formed by the cells of:

Explanation

Ectoderm is formed by the cells of epiblast. The epiblast is a crucial component of the early embryo, specifically in amniotes, which are a group of vertebrates that includes reptiles, birds, and mammals. The term "epiblast" refers to a specific layer of cells in the developing embryo, and its fate and contributions to the developing organism vary among different species. The epiblast is an upper layer of cells in the developing embryo, situated above another layer called the hypoblast or primitive endoderm.During early embryonic development, the epiblast is primarily responsible for giving rise to the three primary germ layers, which are the ectoderm, mesoderm, and endoderm. These germ layers, in turn, develop into various tissues and organs of the body.The contribution and role of the epiblast can differ among species. For example, in mammals, the epiblast forms the embryo proper and plays a central role in the development of the fetus. In birds and reptiles, the epiblast contributes to the formation of the embryo and extraembryonic structures, such as the amnion and the chorion.