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. Also called blastosphere. [New Latin : from Greek blastos, bud + Latin -ula, feminine diminutive suffix.] blas'tu·lar adj., blas'tu·la'tion (-lā'shən) n.

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.

Main Entry: blas·tu·la
Pronunciation: 'blas-ch&-l&
Function: noun
Inflected Form: plural blas·tu·las or blas·tu·lae /-"lE/
: an early metazoan embryo typically having the form of a hollow fluid-filled rounded cavity bounded by a single layer of cells—compare GASTRULA, MORULA —blas·tu·lar /-l&r/ adjective —blas·tu·la·tion /"blas-ch&-'lA-sh&n/ noun

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.

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blas'tu·lar adj.
blas'tu·la'tion (-lā'shən) n.

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.

blastula

hollow sphere of cells, or blastomeres, produced during the development of an embryo by repeated cleavage of a fertilized egg. The cells of the blastula form an epithelial (covering) layer, called the blastoderm, enclosing a fluid-filled cavity, the blastocoel. After the blastula develops, it undergoes transition to the gastrula (q.v.), a process called gastrulation. In organisms such as mammals, the earlier morula (q.v.), a berrylike cluster of cells, develops into a somewhat different form of blastula, the blastocyst (q.v.).

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