from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Any of the blastomeres of an embryo from which the endoderm develops.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any of the embryonic blastomeres that develop into the endoderm
from the GNU version of the Collaborative International Dictionary of English
- n. The inner germ layer; endoderm. See nucleolus.
from The Century Dictionary and Cyclopedia
- n. In biology, the nucleolus of a cell.
- n. In embryology, one of the blastomeres or segments or the egg which takes part in forming the wall of the intestine, or enteron.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the inner germ layer that develops into the lining of the digestive and respiratory systems
Then every mesoblast contracts; the contraction deepens, till it is divided across in both directions, separating thus into four parts, then into eight, then into sixteen, and so on, till every cell is crowded with hundreds of minute mesoblasts, each containing the indication of a central dot or entoblast.
The parietal and visceral mesoblast, or the two middle layers, are always of later origin, and arise through evagination or plaiting of the entoblast, the remainder of which can now be distinguished as secondary entoblast from the primary.
The following passage gives a good idea of their views and of the phylogenetic implications involved: -- "Ectoblast and entoblast are the two primary germ-layers which arise from the invagination of the blastula; they are always the first to be laid down, and they can be directly referred back to a simple ancestral form, the