notochord (chorda dorsalis) Somewhat flexible, rod-like structure, composed of disc-like, turgid cells, which extends virtually the entire length of the body of adult and/or larval members of the phylum Chordata. Lying below the nerve cord, but dorsal to the intestine, the notochord provides a form of flexible support to the body. In vertebrates the notochord is replaced wholly or partly by the vertebral column, but it is retained throughout life in Cephalochordata and Agnatha.

notochord (chorda dorsalis) A some what flexible, rod-like structure, composed of disc-like, turgid cells, which extends virtually the entire length of the body of adult and/or larval members of the phylum Chordata. Lying below the nerve cord, but dorsal to the intestine, the notochord provides a form of flexible support to the body. In vertebrates the notochord is replaced wholly or partly by the vertebral column, but it is retained throughout life in Cephalochordata and Agnatha.

notochord An elastic skeletal rod lying lengthwise beneath the nerve cord and above the alimentary canal in the embryos or adults of all chordate animals (see Chordata). Its function is to strengthen and support the body and act as a protagonist for the muscles. It is found in both adult and larval lancelets but in adult vertebrates it is largely replaced by the vertebral column.

notochord In chordates, such as acorn worms, and the early embryonic stages of vertebrates, the flexible, primitive backbone; in mature vertebrates it is replaced by the spine.