from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A flexible rodlike structure that forms the main support of the body in the lowest chordates, such as the lancelet; a primitive backbone.
- n. A similar structure in embryos of higher vertebrates, from which the spinal column develops.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A flexible rodlike structure that forms the main support of the body in the lowest chordates; a primitive spine
- n. A similar structure found in the embryos of vertebrates from which the spine develops
from the GNU version of the Collaborative International Dictionary of English
- n. An elastic cartilagelike rod which is developed beneath the medullary groove in the vertebrate embryo, and constitutes the primitive axial skeleton around which the centra of the vertebræ and the posterior part of the base of the skull are developed; the chorda dorsalis. See Illust. of ectoderm.
from The Century Dictionary and Cyclopedia
- n. The chorda dorsalis or primitive backbone: a fibrocellular or cartilaginous rod-like structure which is developed in vertebrates as the basis of the future spinal column, and about which the bodies of the future vertebræ are formed.
- n. A vestigial structure, representing a very ancient form of alimentary canal not in itself a part of the skeleton.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a flexible rodlike structure that forms the supporting axis of the body in the lowest chordates and lowest vertebrates and in embryos of higher vertebrates
For example, the notochord is a character that provides internal structural support and unites all members of the phylum Chordata or chordates, animals with notochords and pharyngeal arches, among other characteristics.
A notochord is a rope of nervous connection which branches into the trunk nerves of the body.
Thus the notochord is the necessary forerunner of the vertebral column, cartilage the precursor of bone.
The notochord is a continuous rod of cartilage, or gristle, which in the embryological growth of vertebrate animals supports the spinal nerve cord before the formation of the vertebrae.
The notochord is the supporting axis of the pioneer backboned animals, namely the Lancelets and the Round-mouths (Cyclostomes), such as the
Concomitantly with the development of this canal, there is found, immediately beneath it, a little gelatinous rod enclosed in a membraneous envelope, and called the notochord, or chorda dorsalis.
Amphioxus has only a primitive proto-spinal column called a notochord, but it is a very close relative of vertebrates.
Amphioxus has only a primitive proto-spinal column called a notochord, but it is a very close relative of the vertebrates.
The finding is of particular relevance to the fossils of ancient chordates - animals that develop a characteristic rod-like support structure known as a notochord at some point during their lives.
O. Mangold was able to show that mesodermal organs such as notochord, somites and pronephric ducts could arise from presumptive ectoderm by suitable transplantation at the beginning of gastrulation.