noun, plural blastulas, blastulae [blas-chuh-lee] . Embryology.
the early developmental stage of an animal, following the morula stage and consisting of a single, spherical layer of cells enclosing a hollow, central cavity.
Compare blastocyst.

1885–90; < Neo-Latin < Greek blast(ós) bud, sprout + Neo-Latin -ula -ule

blastular, adjective
blastulation [blas-chuh-ley-shuhn] , noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
blastula (ˈblæstjʊlə)
n , pl -las, -lae
Also called: blastosphere an early form of an animal embryo that develops from a morula, consisting of a sphere of cells with a central cavity
[C19: New Latin; see blasto-]

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Word Origin & History

embryonic state, 1887, Mod.L., from Gk. blastos "sprout, germ" + dim. ending '-ula.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

blastula blas·tu·la (blās'chə-lə)
n. pl. blas·tu·las or blas·tu·lae (-lē')
An early embryonic form produced by cleavage of a fertilized ovum and consisting of a spherical layer of cells surrounding a fluid-filled cavity.

blas'tu·lar adj.
blas'tu·la'tion (-lā'shən) n.
The American Heritage® Stedman's Medical Dictionary
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American Heritage
Science Dictionary
blastula   (blās'chə-lə)  Pronunciation Key 
Plural blastulas or blastulae (blās'chə-lē')
An animal embryo at the stage immediately following the division of the fertilized egg cell, consisting of a ball-shaped layer of cells around a fluid-filled cavity known as a blastocoel. Compare gastrula. See also blastocyst.
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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary
blastula [(blas-chuh-luh)]

The stage of an embryo that consists of just over a hundred cells — a stage reached about one week after fertilization. At this stage the cells are just at the very beginning of cellular differentiation and are said to be totipotent (See totipotency).

Note: This is the stage of development where embryonic stems cells can be harvested for medical research.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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