The ________ is an embryonic midline structure common to all members of the phylum Chordata that serves as a source of midline signals to surrounding tissues and as a major skeletal element of the developing embryo.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. notochord.
The notochord is an embryonic midline structure common to all members of the phylum Chordata. It plays a crucial role during early development by serving as the primary axial support of the embryo and acts as a signaling center that guides the formation of surrounding tissues, including the neural tube and vertebral column. Composed of a rod-like structure made of cells and connective tissue, the notochord extends along the length of the embryo. In most vertebrates, it is eventually replaced by the vertebral column, but its presence is essential for proper body axis formation and organ patterning during embryogenesis.