How To Use Notochord In A Sentence
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First was the relatively simple activation of motoneuron fates by sonic hedgehog from the notochord and floorplate and retinoic acid from the paraxial mesoderm.
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The foregut is here more inclosed, and the notochord, _nt_, having separated from the entoderm, _en_, is seen as a distinct layer of cells extending from the foregut to the blastopore.
Development of the Digestive Canal of the American Alligator
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Many tunicates have a larva that is free-swimming and exhibits all chordate characteristics: it has a notochord, a dorsal nerve cord, pharyngeal slits, and a post-anal tail.
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Thus the notochord, the brain, the eyes, the heart, appear earlier in the ontogenetic than in the phylogenetic series, while, on the other hand, the septum of the auricles appears in the development of the higher Vertebrates before the ventricular septum, which is undoubtedly a reversal of the phylogenetic order.
Form and Function A Contribution to the History of Animal Morphology
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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.
The Common Frog
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A similar pair of parachordal cartilages develop posteriorly from mesoderm, flanking the notochord.
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Thus the notochord is the necessary forerunner of the vertebral column, cartilage the precursor of bone.
Form and Function A Contribution to the History of Animal Morphology
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The foregut is here more inclosed, and the notochord, _nt_, having separated from the entoderm, _en_, is seen as a distinct layer of cells extending from the foregut to the blastopore.
Development of the Digestive Canal of the American Alligator
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That a notochord should develop out of the archenteric wall because a supporting axis would be beneficial to the animal may be a teleological assumption, but it is at the same time an evolutional heresy.
Form and Function A Contribution to the History of Animal Morphology
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A notochord is a rope of nervous connection which branches into the trunk nerves of the body.
Neutron Star
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The hypoblastic notochord is early embraced by a mesoblastic sheath derived from the protovertebrae.
Text Book of Biology, Part 1: Vertebrata
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They all have, at some embryonic stage, a notochord, flanked by muscle, and a dorsal neural tube.
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Amphioxus has only a primitive proto-spinal column called a notochord, but it is a very close relative of the vertebrates.
NPR Topics: News
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Further experiments showed that it is the notochord primordia which organize the development of the primordial spinal cord, while, on the other hand, the mesoderm in the head causes the development of a primordial brain.
Physiology or Medicine 1935 - Presentation Speech
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Such a floppy, sheathless notochord cannot push effectively on the surrounding embryonic tissues, but rather folds up like a wet noodle as it elongates relative to the surrounding embryo.
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But the notochord in the fowl is not so distinctly connected with the hypoblast, and so distinct from the mesoblast, as it is in the lower type, and no gills, internal or external, are ever developed.
Text Book of Biology, Part 1: Vertebrata
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Background Extra - axial chordomas are rare low - grade malignant tumors thought to arise from notochordal remnants extra - axial skeleton.
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This takes the vertebrate embryo up to the stage at which it has become recognizably vertebrate, with somites, notochord, and neural tube.
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In the evolution of vertebrates, long bodies with continuously flexible notochords and segmental muscles existed before the appearance of segmental vertebrae.
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These are separated from one another by intersegmental septa and are arranged symmetrically on either side of the neural tube and notochord: to every segment a spinal nerve is distributed.
II. Osteology. 1. Development of the Skeleton
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Yet in vertebrates, as the notochord is forming during a developmental process called gastrulation, it first functions to establish the midline of the embryo.
Haeckel had a point - The Panda's Thumb
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In those chordates which lack bone, muscles work against the notochord to move the animal.
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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.
Scientific American
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Before throwing tail and hinder part of body away, note the myotomes of body wall, the notochord and vertebral body, neural canal, and, in the tail, the haemal canal.
Text Book of Biology, Part 1: Vertebrata
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They lack two others, the notochord and post-anal tail, hence the name hemichordate.
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Most members of the chordate phylum, those in the subphylum Vertebrata, replace the notochord with vertebrae (the backbone) later in development to support the pelvic and pectoral girdles (to which the front and hind limbs are attached) and to protect the spinal cord.
Haeckel had a point - The Panda's Thumb
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In the evolution of vertebrates, long bodies with continuously flexible notochords and segmental muscles existed before the appearance of segmental vertebrae.
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The most affected tissue being dorsal mesoderm; the notochord is disrupted and the tailbud fails to form.
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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 Elements of Geology
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The determination and differentiation of notochord in Bufo bufo gargarizans embryos in different developmental stage have been systematically studied.
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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.
Haeckel had a point - The Panda's Thumb
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Lastly, all chordates have a post-anal tail, or extension of the notochord and nerve cord past the anus.
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The cells of this layer proliferate rapidly, and extending medialward surround the notochord; at the same time they grow backward on the lateral aspects of the neural tube and eventually surround it, and thus the notochord and neural tube are enveloped by a continuous sheath of mesoderm, which is termed the membranous vertebral column.
II. Osteology. 1. Development of the Skeleton
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The cells of this layer proliferate rapidly, and extending medialward surround the notochord; at the same time they grow backward on the lateral aspects of the neural tube and eventually surround it, and thus the notochord and neural tube are enveloped by a continuous sheath of mesoderm, which is termed the membranous vertebral column.
II. Osteology. 1. Development of the Skeleton
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Let us review the fundamental features of the vertebrate body as context for notochords and backbones.
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_ -- About the middle of the first month of intra-uterine life the prosencephalon bends acutely forward over the end of the notochord and sends out from its base a series of processes, which ultimately blend to form the face (Fig. 231).
Manual of Surgery Volume Second: Extremities—Head—Neck. Sixth Edition.
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The notochord is the supporting axis of the pioneer backboned animals, namely the Lancelets and the Round-mouths (Cyclostomes), such as the
The Outline of Science, Vol. 1 (of 4) A Plain Story Simply Told
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But in coelacanths, lungfishes and some primitive sharks, the transformation of notochord into a segmented bony vertebral column does not take place.
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The notochord sheath is a collagenous connective tissue.
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Notably, the oldest known Early Cambrian chordate Yunnanozoon had its metameric muscular units located dorsally of the notochord, although its body was laterally compressed.
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At this time he considered _Balanoglossus_ -- by reason of its gill-slits (its notochord he did not know) -- to be the nearest living representative of the ancestral form of Vertebrates and Annelida.
Form and Function A Contribution to the History of Animal Morphology
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The presumptive neural tube tissues consist of a layer of ectoderm along the dorsal midline of the embryo, between the notochord and an outer layer of epidermis.
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Notochords are the axial skeleton of invertebrate chordates (cephalochordates, appendicularians, and tadpole larvae of ascidians), of agnathan fish, and of amphibian tadpoles.
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Amphioxus has only a primitive proto-spinal column called a notochord, but it is a very close relative of vertebrates.
NPR Topics: News
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This is the architecture that supports and is supported by the vertebrate axis, namely the notochord or vertebral column.
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The hypoblast is the lining of the intestine and of the glands which open into it; and the material of the notochord is also regarded, as hypoblast.
Text Book of Biology, Part 1: Vertebrata
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As for a pathway from a simple notochord to a human brain, you need only study the developing human embryo.
Assessing Fault
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The intervertebral discs develop embryologically from both the mesenchyme (the annulus fibrosus) and the notochord (the nucleus pulposus).
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Myogenesis in the paraxial muscles (dorsal compartment) is dependent on contact with the neural tube and notochord, while limb and abdominal muscles (ventral compartment) are not.
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The entoderm, which has the appearance of being thickened because of the fact that the notochord has not yet completely separated from it, is continuous, through the blastopore, with the ectoderm.
Development of the Digestive Canal of the American Alligator
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A shallow fossa is occasionally found on the ventral surface of the basilar portion anterior to the pharyngeal tubercle, which has been interpreted as a vestige of the canal of the notochord.
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The only competing hypothesis - chaetognath affinity - provides some alternative interpretations; but the dorsal notochord, tail, and fin radials make this unlikely.
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With the notochord he homologised the supporting rod in the proboscis of _Balanoglossus_, which like the notochord arises from the dorsal wall of the archenteron, and has a vacuolated structure.
Form and Function A Contribution to the History of Animal Morphology
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Moreover, these ectopic neural tubes were patterned appropriately with respect to the notochord and dorsal ectoderm.
