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One of the large blastomeres found in a developing embryo.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Biology) embryol any of the large yolk-filled cells formed by unequal cleavage of a fertilized ovum
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈmæk rəˌmɪər)

one of the blastomeres that form toward the vegetal pole in embryos undergoing unequal cleavage.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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Similarly in mollusks the stem cell of the mesentoblast (macromere 3D) and its daughter cell (mesentoblast 4d) act as organizers and specify the developmental fate of a large number of blastomeres (Damen 1994, Damen and Dictus 1994a,b).
In equal-cleaving embryos without polar lobes the dorsal (D) cell quadrant is determined later during development by virtue of cell-cell inductive interactions between derivatives of the first quartet micromeres (la1-Id") and one of the vegetal macromeres (presumptive 3D macromere) after the birth of the third quartet (van den Biggelaar and Guerrier, 1979; Arnolds et al., 1983; Martindale et al, 1985; Kuhtreiber et al., 1988; Boring, 1989; van den Biggelaar, 1996; Henry, 2002).
obsoleta Hb-like proteins are expressed in every micromere and macromere nucleus from one cell to at least the sixth cleavage division.
During second cleavage, the macromere with most of the red cytoplasm failed to separate completely at its vegetal pole (Fig.
Classical experiments performed on gastropod embryos demonstrate that the D macromere plays a critical role in axial patterning as the founder cell of the dorsal lineage.
It is not clear how morphogenesis of the rest of the gut (e.g., mouth and stomodaeum) might be affected by macromere ablation, but it is possible that a simple reduction of endodermal cell volume might permit the development of a complete larval gut.
At this stage, the embryo is designated a morula, and the uniformly distributed pigment granules become unevenly distributed to specific cells, with most going to the 8 macromere cells.
3D) and gave rise to micromeres and macromeres. The cleavage was total and spiraled, and no polar lobes were observed.
Asi, reconocen las series Macromeres, Aulacothelae y Glanduliferae.
rosaceus follows the typical pattern for echinoids with planktotrophic larvae, beginning with three equal cleavages followed by the formation of mesomeres, macromeres, and micromeres at the 16-cell stage (Fig.