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One of the small blastomeres found in a developing embryo.


(Biology) embryol any of the small cells formed by unequal cleavage of a fertilized ovum


(ˈmaɪ krəˌmɪər)

one of the small blastomeres that form toward the animal pole in embryos that undergo unequal cleavage.
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Juliano CE, Voronina E, Stack C, Aldrich M, Cameron AR (2006) Germ line determinants are not localized early in sea urchin development, but do accumulate in the small micromere lineage.
Spatial aspects of cell interactions involved in the determination of dorsoventral polarity in equally cleaving gastropods and regulative abilities of their embryos, as studied by micromere deletions in Lymnaea and Patella.
A regulatory gene network that directs micromere specification in the sea urchin embryo.
A Ral/MEK/ERK signaling pathway is required for development of the sea urchin embryo micromere lineage through phosphorylation of the transcription factor Ets.
For instance, addition of a single micromere to isolated rings of animal or vegetal cells resulted in a ciliated blob, whereas the addition of four micromeres resulted in a normal pluteus.
The fourth cleavage appeared asynchronous: the macromeres divided first to produce a transient 12-cell stage, followed by a 13-cell stage as one first-quartet micromere consistently divided before the other three (Fig.
The 4d micromere plays a significant role, giving rise to the paired mesentoblast cells MEL and MER.
obsoleta Hb-like proteins are expressed in every micromere and macromere nucleus from one cell to at least the sixth cleavage division.
Molluscs, like most other lophotrochozoans, exhibit a highly conserved pattern of spiral cleavage that generates four macromeres surmounted by four tiers of micromere quartets.
Pmarl drives specification of skeletogenic cells-- the micromere descendants (Oliveri et al.
It remained attached to the vegetal pole of the embryo as a spherical packet of red-colored cytoplasm ("red body") at least through the period when micromere quartets were generated (Fig.
Micromere differentiation in the sea urchin embryo: expression of primary mesenchyme cell specific antigen during development.