notochord

notochord
—notochordal, adj.
/noh"teuh kawrd'/, n. Embryol.
a rodlike cord of cells that forms the chief axial supporting structure of the body of the lower chordates, as amphioxus and the cyclostomes, and of the embryos of the vertebrates.
[1840-50; NOTO- + CHORD]

* * *

      flexible rodlike structure of mesodermal cells that is the principal longitudinal structural element of chordates and of the early embryo of vertebrates, in both of which it plays an organizational role in nervous system development. In later vertebrate development, it becomes part of the vertebral column. The notochord derives during gastrulation (infolding of the blastula, or early embryo) from cells that migrate anteriorly in the midline between the hypoblast and the epiblast (inner and outer layers of the blastula). These cells coalesce immediately beneath the developing central nervous system. With the formation of the vertebral column, the notochord is incorporated into the column as the centres of the intervertebral discs, called the nuclei pulposi, which cushion the vertebrae.

* * *


Universalium. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Notochord — Transverse section of a chick embryo of forty five hours’ incubation. Latin notochorda Gray s …   Wikipedia

  • Notochord — No to*chord, n. [Gr. nw^ton the back + E. chord.] (Anat.) 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… …   The Collaborative International Dictionary of English

  • Notochord — Notochord, s. Chorda dorsalis …   Meyers Großes Konversations-Lexikon

  • Notochórd — (grch.), Wirbelsaite, s. Chorda …   Kleines Konversations-Lexikon

  • notochord — (n.) 1848, coined in English by English anatomist Sir Richard Owen (1804 1892) from CHORD (Cf. chord) + comb. form of Gk. noton back, from PIE *not buttock, back (Cf. L. natis buttock, sopurce of It., Sp. nalga, O.Fr. nache buttock, butt ) …   Etymology dictionary

  • notochord — [nōt′ə kôrd΄] n. [ NOTO + CHORD1] 1. an elongated, rod shaped structure composed of cells, forming the primitive supporting axis of the body in the lowest chordates and lying between the digestive tract and the central nervous system 2. a similar …   English World dictionary

  • Notochord — Bauplan eines Lanzettfischchen mit Chorda dorsalis (2) zwischen dem Neuralrohr (1, 3) und dem Kiemendarm (6, 9, 11) Die Chorda dorsalis („Rückensaite“; von lat. chorda bzw. griech. chorde „Darm“, „Darmsaite“ und lat. dorsum „Rücken“), auch… …   Deutsch Wikipedia

  • notochord — the skeletal rod consisting of a sheath firmly packed with cells which lie above the gut and below the nerve cord. The notochord is persistent when it remains as a continuous skeletal support (e.g. Amphioxi, Holocephali, Acipenseridae,… …   Dictionary of ichthyology

  • notochord length — the distance from the snout tip to the posterior tip of the notochord. Abbreviated as NL …   Dictionary of ichthyology

  • notochord — noun Etymology: Greek nōton, nōtos back + Latin chorda cord more at cord Date: 1848 a longitudinal flexible rod of cells that in the lowest chordates (as a lancelet or a lamprey) and in the embryos of the higher vertebrates forms the supporting… …   New Collegiate Dictionary

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”