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: -The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the outer layer of germ cells.

Detailed explanation-3: -Regardless of the presence of two or three layers, endoderm is always the inner-most layer. Endoderm forms the epithelium-a type of tissue in which the cells are tightly linked together to form sheets-that lines the primitive gut.

Detailed explanation-4: -ectoderm, the outermost of the three germ layers, or masses of cells, which appears early in the development of an animal embryo.

Detailed explanation-5: -The ectoderm generates the outer layer of the embryo, and it forms from the embryo’s epiblast. The ectoderm develops into the surface ectoderm, neural crest, and the neural tube.