HHP 1110 Lecture Notes - Primitive Streak, Primitive Knot, Epiblast

• School: University of Iowa
• Department: Health and Human Physiology
• Course: HHP 1110

Document Summary

Embryology: events of the embryonic & fetal periods ch 3 b the embryonic period. Begins w/ establishment of 3 primary layers. By end of embryonic period, main organ systems are developed. Gastrulation: process by which cells from the epiblast migrate to form the primary germ layers (week 3) Starts w/ formation of the primitive streak. Primitive node: cephalic end of the primitive streak. Primitive pit: a depression in the node. Once all 3 primary germ layers are present (ectoderm, mesoderm, endoderm) the structure can be called an embryo. Invagination: inward movement of cells from epiblast layer through primitive streak btwn epiblast & hypoblast layers. Cells btwn the epiblast & hypoblast layers become the primary germ layer (mesoderm) Other migrating cells displace the hypoblast cells & become endoderm. Cells remaining in the epiblast will become ectoderm. All 3 germ layers are derived from the epiblast embryonic disc: formation neurulation. Formation of the neural tube begins w/ the appearance of the notochord.