What is the outermost embryonic germ layer that eventually forms the nervous system?

The outermost embryonic germ layer that gives rise to the nervous system is the ectoderm. During embryonic development, the ectoderm is responsible for forming structures such as the skin, hair, nails, and the entire nervous system, including the brain and spinal cord. This process of nervous system formation is known as neurulation, where the ectoderm differentiates into neuroectoderm and ultimately leads to the development of neural tissues.

The endoderm, on the other hand, primarily forms the lining of the digestive and respiratory tracts as well as associated organs such as the liver and pancreas. The mesoderm contributes to the formation of muscle, skeleton, circulatory system, and other connective tissues. The term "amnioderm" is not recognized as a standard embryonic germ layer in classical embryology and is likely an incorrect option. Therefore, the ectoderm is indeed the correct answer due to its crucial role in the development of the nervous system.