title: The retention of primary hypoblastic cells underneath the developing primitive streak allows for their prolonged inductive influence.
abstract: An experimental study was made of the distribution of the primary hypoblastic cells in the lower layer of the avian blastoderm throughout primitive streak formation and until stage 10 (Hamburger & Hamilton, 1951). The primary hypoblast of stage XIII (Eyal-Giladi & Kochav, 1976) chick blastoderms was exchanged for either an [H3]thymidine-labelled similar chick hypoblast, or a quail primary hypoblast. During the entire period of primitive streak formation, the lower layer proved to be a mosaic of labelled hypoblastic and non-labelled entodermal cells (chick cells of epiblastic origin). The persistance of hypoblastic cells underneath the developing primitive streak is regarded by us as a possible way to prolong the inductive influence of the hypoblast upon the forming streak.
mesh_terms: D000818:Animals; D001756:Blastoderm / Q000166:cytology*; D002465:Cell Movement; D002642:Chick Embryo; D002678:Chimera; D005775:Gastrula / Q000166:cytology*; D009024:Morphogenesis; D011784:Quail / Q000196:embryology; D013936:Thymidine; D013997:Time Factors; D014316:Tritium
chemical_list: D014316:Tritium; D013936:Thymidine