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gastrula
Book article from: A Dictionary of Nursing
gastrula ( gas -troo-lă) n. an early stage in the development of many animal embryos. The gastrula consists of a double-layered ball of cells formed by invagination and movement of cells in the preceding single-layered stage...
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Beneden, Edouard Van
Dictionary entry from: Complete Dictionary of Scientific Biography
...tendency to sometimes bold generalization. At that time, the gastrula theory of metazoan development was presented by Huxley, Lankester...their structure and observed that they derive from an epibolic gastrula, the hypoblast of which is formed by a long, central single...
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Kovalevsky, Aleksandr Onufrievich
Dictionary entry from: Complete Dictionary of Scientific Biography
...ascidians, and amphioxi — develop from a bilaminar sac (gastrula) produced by invagina. tion. His work also showed that later...Kovalevsky ’ s conclusion into his own theory of the gastrula; and by Darwin, who saw them as providing embryological proofs...
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Castle, William Ernest
Dictionary entry from: Complete Dictionary of Scientific Biography
...embryonic state of every cell from first cleavage through late gastrula. Castle took issue with the prevailing view of the origin...chordates originates from pouches in the infolded endoderm of the gastrula, in a manner similar to that in the echinoderms. Ciona is...
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pilidium larva In
Book article from: A Dictionary of Zoology
pilidium larva In Nemertini , a free-swimming larva which develops directly from the gastrula .
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germ layers
Book article from: A Dictionary of Zoology
germ layers In an embryo at the gastrula stage, the layers of cells that will develop to form the organs of the body. See GASTRULATION .
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pharangula
Book article from: A Dictionary of Zoology
...gill slits, whilst in most tetrapods these regions give rise to the tympanic membrane , glands associated with the lymphatic system such as the thymus gland, parathyroid gland, carotid bodies, and tonsils. See also BLASTULA ; GASTRULA .
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blastula
Book article from: A Dictionary of Biology
...embryo forming a layer ( blastoderm ) around a central cavity ( blastocoel ). In vertebrates the blastula forms a disc ( blastodisc ) on the surface of the yolk. In mammals the blastula stage is known as a blastocyst . See also gastrula .
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skeletagenous septum
Book article from: A Dictionary of Zoology
...notochord; horizontal septa bisect this plane perpendicularly. Mesenchymal cells migrate to the skeletagenous septa during the gastrula stage of embryogenesis to form sclerotomic tissue (see SOMITE ). At the junction between the myoseptum and skeletagenous...
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archenteron
Book article from: A Dictionary of Biology
archenteron ( gastrocoel ) A cavity within an animal embryo at the gastrula stage of development. All or part of the archenteron eventually forms the cavity of the gut. It is connected to the outside by...
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