AP BIOLOGY

Detailed explanation-1: -The ectoderm is the outer layer of the embryo, which gives rise to the external ectoderm (epidermis, hair, nails) and the neuroectoderm (neural crest and neural tube-brain and spinal cord), along with the lens of the eyes and the inner ear.

Detailed explanation-2: -During gastrulation, a hollow cluster of cells called a blastula reorganizes into two primary germ layers: an inner layer, called endoderm, and an outer layer, called ectoderm.

Detailed explanation-3: -Generally speaking, the ectoderm differentiates to form epithelial and neural tissues (spinal cord, peripheral nerves and brain). This includes the skin, linings of the mouth, anus, nostrils, sweat glands, hair and nails, and tooth enamel. Other types of epithelium are derived from the endoderm.

Detailed explanation-4: -ec·to·derm ˈek-tə-ˌdərm. : the outermost of the three primary germ layers of an embryo that is the source of various tissues and structures (such as the epidermis, the nervous system, and the eyes and ears) : a tissue (such as neural tissue) derived from this germ layer.

Detailed explanation-5: -Three primary germ layers Gastrulation is a key phase in embryonic development when pluripotent stem cells differentiate into the three primordial germ layers: ectoderm, mesoderm and endoderm.