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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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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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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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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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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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primitive streak
Book article from: A Dictionary of Biology
primitive streak The longitudinal groove that develops in the gastrula during the development of bird and mammal embryos. The cells in the primitive streak proliferate rapidly to form mesoderm cells, which migrate to the interior of the embryo.
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organizer
Book article from: A Dictionary of Biology
organizer An area of an animal embryo that causes adjacent areas of the embryo to develop in a certain way. The primary organizer (blastopore lip or archenteron roof) causes the gastrula to develop as a complete organism.
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ectoderm
Book article from: A Dictionary of Biology
ectoderm The external layer of cells of the gastrula , which will develop into the epidermis and the nervous system in the adult. See also germ layers .
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Brachet, Albert
Dictionary entry from: Complete Dictionary of Scientific Biography
...region of the blastopore becomes the active center of development of the embryonic body. In the vertebrates, however, the gastrula stage is so modified that it is recognizable only with difficulty. Brachet made notable contributions to the solution of this...
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Duval, Mathias Marie
Dictionary entry from: Complete Dictionary of Scientific Biography
...evolution. His research in this area reflects his training as a histologist and physiologist: it concerned the formation of the gastrula, development of the blastoderm, the three primitive germ layers and their derivatives in the various species, segmentation...
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