Which germ layer is responsible for forming the neural tube and neural crest?

The ectoderm is the correct germ layer responsible for forming the neural tube and neural crest during embryonic development. As the outermost layer of the three primary germ layers, the ectoderm differentiates into various structures, including the skin and the nervous system.

During the process of neurulation, the ectoderm folds to create the neural tube, which ultimately develops into the central nervous system, comprising the brain and spinal cord. Additionally, the neural crest, which originates from the edges of the neural tube, gives rise to various structures, including peripheral nerves, some endocrine cells, and pigment cells.

The mesoderm mainly contributes to forming the muscles, bones, and circulatory system, while the endoderm primarily forms internal organs, such as the digestive tract and respiratory system. The term "exoderm" is not a recognized germ layer in embryology, hence it is not a viable option. Understanding the differentiation roles of these germ layers is crucial for grasping embryological development and the origins of various tissues and organs in the body.