Neurulation in the chick, after the node regresses

Typical vertebrate organization of the chick embryo(and >200 selector gene domains)**Or wait until the embryo lifts off the yolk sacNotochordSomatic mesodermVisceral mesoderm

Extra-embryonic membranes of the chick

Amnion and chorion: contain ectoderm and somatic mesodermYolk sac and allantois: contain enododerm and visceral mesoderm

Chick development: Formation of the allantois

Human or mouse embryo: pre-implantation stages4. hatching1. compactiongene expression starts128 cellDay 7-humanDay 5.5-mouse22. Blastocyst cavity formation3. Cell sorting (hypo vs. epi)

Mouse pre-implantation stages: compaction, apical-basal polarization, cleavage, blastocyst cavity formationCompaction at the late 8-cell stage, With apical-basal polarization of cells128-cell blastocystcompaction128-cell blastocyst

Human 128cell blastocyst before/during hatchingMouse embryonic stem cells (ES cells)from the inner cell mass, growing in a culture dishInjection of ES cells into theblastocyst cavityzonaHolding pipetInjection pipetOct4 gene expression in epiblast

Mouse transgenesis (insertion of a foreign gene into the mouse genome)Dr. MarioCapecchi-1984Univ. of UtahGene for red fluorescent protein (RFP)Gene for green fluorescentprotein (GFP) from jellyfish(e.g., GFPwith promoter)FOSTER MOTHER(2x)(random)non-homologous integrationGreen ES cells

Implantation of the human blastocyst in the uterine wall. Mouse implantation is also invasive, like humanSyncytio-trophoblastMaternaltissueUterinefluid

Role of the AVE (anterior visceral endoderm) in establishing the anterior-posterior axis of the mouse embryoCylindrical SymmetryBilateral SymmetryAPCerberus (anti-Nodal)Dkk (anti-Wnt)Lefty (anti-Nodal)Otx2Anterior neural ectodermNodal, Vg1,Cripto (co-receptorFor Nodal and Vg1)Endo-mesoderminductionDay 5.25 Day 5.5 Day 6.25orhypoblastEndo-mesoderm induction,Primitive streakNodal, wnt, brachyury, fgf expressedEpiblastectoderm