from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Embryology Exhibiting cleavage in which the entire egg separates into individual blastomeres.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Cleaving, and separating into separate blastomeres.
from the GNU version of the Collaborative International Dictionary of English
- adj. Undergoing complete segmentation; composed entirely of germinal matter, the whole of the yolk undergoing fission; -- opposed to meroblastic.
from The Century Dictionary and Cyclopedia
- Wholly germinal: applied by Remak to those eggs in which the whole yolk is formative—that is, undergoes segmentation in development: opposed to meroblastic. Mammals, excepting monotremes, have holoblastic eggs. See cut under gastrulation.
In the mammalian ova the nutritive yolk or deutoplasm is small in amount and uniformly distributed throughout the cytoplasm; such ova undergo complete division during the process of segmentation, and are therefore termed holoblastic.
WHOLE cell; hence Remak called it TOTAL segmentation, and the ova in question holoblastic, or "whole-cleaving."
Although the mass of the food-yelk may be very large in the ova of the discoblastic vertebrates, nevertheless in every case a blastula is developed from the morula, as in the holoblastic ova.
The multiplicity or loss of the vitellogenin (vtg) gene family in vertebrates has been argued to have broad implications for the mode of reproduction (placental or non-placental), cleavage pattern (meroblastic or holoblastic) and character of the egg (pelagic or benthic).
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