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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 suff.]

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


(Biology) embryol the process of blastula formation
References in periodicals archive ?
2] are smaller and less likely to complete development postfertilization, with embryos arrested prior to blastulation containing more triglyceride than those forming blastocysts.
The continuous monitoring of the progress of the embryo development is possible by following the key indicators of this process (both positive and negative) such as formation of the pronucleus, early cleavage, cell cycle intervals, synchronization of cell division and initiation of blastulation, and multinucleation, etc.
3###16 Cell stage###Fourth Cleavage, moved towards the blastulation
Both genomic DNA and mitochondrial DNA in spent medium were significantly correlated with fragmentation rate, one of the morphologic parameters conventionally used for assessing embryo quality, and mitochondrial DNA mirrored the blastulation potential of both fragmented and high-grade embryos.
Therefore, high ammonia in the culture media at the time of compaction and blastulation may reduce the availability of ATP for embryonic cells during a stage of development when energy demands by the embryo are high, resulting in increased degenerate ova and decreased blastocyst stages.