micromere

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micromere

 [mi´kro-mēr]
one of the small blastomeres formed at the animal pole by unequal cleavage of a fertilized ovum; see also macromere.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

mi·cro·mere

(mī'krō-mēr),
A blastomere of small size; for example, one of the blastomeres at the animal pole of an amphibian egg.
[micro- + G. meros, a part]
Farlex Partner Medical Dictionary © Farlex 2012

micromere

(mī′krō-mîr′)
n.
One of the small blastomeres found in a developing embryo.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

mi·cro·mere

(mī'krō-mēr)
A small blastomere (e.g., one of the blastomeres at the animal pole of an amphibian egg).
[micro- + G. meros, a part]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

micromere

any of the small BLASTOMERES formed at the animal pole of a developing egg. These eventually give rise to the ECTODERM.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
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References in periodicals archive ?
The first is a conditional specification resulting from of an inductive interaction between the animal micromeres and a centralized 3M macromere.
The first mesenchyme cells to ingress are called primary mesenchyme and are derived from the small micromeres that arise at the vegetal pole of the embryo during an unequal fourth cleavage.
Three additional quartets of micromeres are formed (2a-2d, 3a-3d, and 4a-4d; Fig.
collaris, and embryos lack obvious signs of cleavage arrest in the cells that would be the primary trochoblasts in a canonical spiralian (the granddaughters of the l[q.sup.2] cells, which themselves are the vegetal daughters of the first quartet of micromeres formed at third cleavage).
Fate maps of the first quartet micromeres in the gastropod Ilyanassa obsolete.
The recent identification of HesC as the Repressor of Micromeres may be typical of the impact the sea urchin genome has for studies that are not directly concerned with the genome.
However, unequal distribution of red cytoplasm within the four macromeres resulting from second cleavage is not consistent with the notion that the initial four macromeres of equally cleaving gastropod eggs are identical prior to later induction of the dorsoventral axis by micromeres. This non-identity among macromeres may not affect which of the macromeres later becomes the D macromere, but it may result in some subtle but unknown phenotypic difference among the resulting larvae.
Spicules of the sea urchin embryo are synthesized by primary mesenchyme cells (PMCs), which are descendants of the micromeres of the 16-cell-stage embryo (Gustafson and Wolpert, 1967; Okazaki, 1975; Ettensohn et al., 1997).
Recently, MAP kinase (MAPK) signaling cascades in the gastropod Ilyanassa obsoleta have been linked to cell fate specification within the D macromere lineage and the micromeres of the A, B, and C quadrants (Lambert and Nagy, 2001).
As a result of unequal cleavages from the third through the fifth cleavage cycles, these cells, known as macromeres, are usually far larger than the remaining embryonic cells, the micromeres. At gastrulation, the macromeres and their descendants are internalized, where they form the larval midgut (Kume and Dan, 1968; Anderson, 1973).
Third cleavage was equatorial (= perpendicular to the animal-vegetal axis), resulting in four micromeres at the animal pole (la-1d); the four macromeres remained at the vegetal pole (lA-1D) (Fig.
Apical ciliary structures in veliger larvae of apogastropods have been difficult to reconcile with the condition in larvae of patellogastropods and of many other molluscan classes, where a long apical tuft of nonmotile cilia is produced by some or all of the apical rosette micromeres of the embryo (see Raven, 1966; van Dongen and Geilenkirchen, 1974; Verdonk and van den Biggelaar, 1983; Dohmen, 1992; Dictus and Damen, 1997).