Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.


the innermost of the three primary germ layers of the embryo; from it are derived the epithelium of the pharynx, respiratory tract (except the nose), digestive tract, bladder, and urethra. Called also endoblast, entoderm, entoblast, and hypoblast.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


Cell layer adjacent to the yolk sac cavity and subjacent to the epiblast of a bilayered embryo.
[hypo- + G. blastos, germ]
Farlex Partner Medical Dictionary © Farlex 2012



hy′po·blas′tic adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


The innermost of the three primary germ layers of the embryo (ectoderm, mesoderm, endoderm); from it are derived the epithelial lining of the primordial gut and the epithelial component of the glands and other structures (e.g., lower respiratory system) that develop as outgrowths from the gut tube.
Synonym(s): entoderm, hypoblast.
[endo- + G. derma, skin]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


the innermost germ layer in a GASTRULA.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Mouse embryo has the shape of an egg cylinder (showing the apposition the epiblast and visceral endoderm tissues) and human embryo has the shape of a flat disc with two layers of cells known as epiblast and hypoblast. VE: visceral endoderm.
As noted earlier, after blastocoele formation the hypoblast forms the yolk sac and the epiblast begins to differentiate into the three major germ cell layers.
It is of interest to point out that, prior storage, heating the chick eggs for six hours (Fasenko et al., 2001a; Silva et al., 2008) and the turkey, for 12 h (Fasenko et al., 2001b) allowed the complete formation of hypoblast. In the recent decades, several studies reported that pre-heating of poultry eggs before storage resulted in more live chicks and a lower level of embryonic mortality compared to the eggs that remained un-heated (Petek and Dikmen, 2004; Reijrink et al., 2009).
Hypoblast The layer of cells that is situated next to the yolk sac and below the epiblast of the embryo.