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[blas-tuh-sist] /ˈblæs tə sɪst/
noun, Embryology.
the blastula of the mammalian embryo, consisting of an inner cell mass, a cavity, and an outer layer, the trophoblast.
Origin of blastocyst
First recorded in 1885-90; blasto- + -cyst Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for blastocyst


noun (embryol)
Also called blastosphere. the blastula of mammals: a sphere of cells (trophoblast) enclosing an inner mass of cells and a fluid-filled cavity (blastocoel)
another name for germinal vesicle
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for blastocyst

1876, from blasto- + cyst.

Online Etymology Dictionary, © 2010 Douglas Harper
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blastocyst in Medicine

blastocyst blas·to·cyst (blās'tə-sĭst')
The modified blastula stage of mammalian embryos, consisting of the inner cell mass and a thin trophoblast layer enclosing the blastocoel. Also called blastodermic vesicle.

blas'to·cys'tic adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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blastocyst in Science
The modified blastula that is characteristic of placental mammals. It has an outer layer, known as a trophoblast, that participates in the development of the placenta. The inner layer of cells develops into the embryo.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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