BIO380H5 Chapter Notes -Yolk Sac, Primitive Knot, Neurulation
Document Summary
Gene expression changes regulate formation of embryonic axes and organization set up cellular and tissue relationships. Icm delamination separates epiblast and hypoblast prior gastrulation and implantation. New relationships between cells form allowing inter-cellular communications. Hypoblast is flat and contribute to yolk sac epiblast is bilaminate, cuboidal and form embryo. The role of gastrulation convert epiblast to ectoderm, mesoderm, and endoderm. Human gastrulation: how do we know how it works? series of defined cell movements with specific changes in cell shape contribute to elongation of embryo researchers use fluorescently label cells to follow movements, and confocal microscopy. Gastrulation in human embryo first cells move along surface to center line, and enter the embryo forms a bump called primitive node (node) these cells become the notochord. Primitive streak forms behind node first cells entering becomes endoderm, displace hypoblast cells later cells entering becomes mesoderm cells remaining on the surface becomes ectoderm or neural ectoderm.
