ANAT20006 Lecture Notes - Lecture 2: Primitive Streak, Epiblast, Primitive Knot

• School: University of Melbourne
• Department: Anatomy and Neuroscience
• Course: ANAT20006
• Professor: Charles Sevigny

Document Summary

Cleavage- cell divides without growth so they get smaller each time until you get the morula. Outer epithelial layer (trophoblast) forms extraembryonic structures (placenta) Between 5 and 10 days, blastocyst implants into uterine wall. Two germ layer stage (epiblast (upper) and hypoblast) Formation of primitive streak: defines all major body axes. On upper surface of bilaminar disc (on epiblast) a line of thickened cells appear (primitive streak) which then invaginates to form primitive groove. First cells move into hypoblast to form endoderm. Later cells become mesoderm between epiblast and endoderm. Organs are mirrored from their normal position. Cranial midline extension from primitive node to form hollow tube. Tube grows in length (cells added from primitive node) If pri(cid:373)itive streak does(cid:374) t disappear you ca(cid:374) get terato(cid:373)as. Ectodermal cells differentiate into thick plate of pseudostratified, columnar neuroepithelial cells = neuroectoderm. Cranial end swells forming vesicles which becomes the brain.