Embryonic inner cell mass tissue that forms the yolk sac and, later, chorion
In amniote embryology , the hypoblast is one of two distinct layers arising from the inner cell mass in the mammalian blastocyst ,[ 1] [ 2] or from the blastodisc in reptiles and birds . The hypoblast gives rise to the yolk sac , which in turn gives rise to the chorion .[ 3]
The hypoblast is a layer of cells in fish and amniote embryos. The hypoblast helps determine the embryo's body axes , and its migration determines the cell movements that accompany the formation of the primitive streak , and helps to orient the embryo, and create bilateral symmetry .
The other layer of the inner cell mass, the epiblast , differentiates into the three primary germ layers , ectoderm , mesoderm , and endoderm .
^ Palmer, N.; Kaldis, P. (2016-01-01), DePamphilis, Melvin L. (ed.), "Chapter One - Regulation of the Embryonic Cell Cycle During Mammalian Preimplantation Development" , Current Topics in Developmental Biology , Mammalian Preimplantation Development, 120 , Academic Press: 1–53, doi :10.1016/bs.ctdb.2016.05.001 , PMID 27475848 , retrieved 2020-10-16
^ Keefe, David L.; Winkler, Nurit (2007-01-01), Sokol, Andrew I.; Sokol, Eric R. (eds.), "Chapter 1 - Embryology" , General Gynecology , Philadelphia: Mosby, pp. 1–20, doi :10.1016/b978-032303247-6.10001-2 , ISBN 978-0-323-03247-6 , retrieved 2020-10-16
^ Hafez, S. (2017-01-01), Huckle, William R. (ed.), "Chapter One - Comparative Placental Anatomy: Divergent Structures Serving a Common Purpose" , Progress in Molecular Biology and Translational Science , Molecular Biology of Placental Development and Disease, 145 , Academic Press: 1–28, doi :10.1016/bs.pmbts.2016.12.001 , PMID 28110748 , retrieved 2020-10-16