Final answer:
The notochord, derived from the mesoderm, signals the ectodermal cells and plays a role in embryonic development. Mesoderm gives rise to muscle cells and connective tissue in the body.
Step-by-step explanation:
The notochord, which is derived from the mesoderm, plays a crucial role in embryonic development. It signals the ectodermal cells to form epidermal cells as well as the neural plate. Additionally, the mesoderm gives rise to muscle cells and connective tissue in the body, such as the axial skeleton and skeletal muscle.