Embryology

    Cards (7)

    • Gastrulation - week 3
      1. Epiblast cells form primitive streak and move down into hypoblast
      2. The hypoblast layer is displaced forming the endoderm
      3. Some epiblast cells move between the epiblast and hypoblast to form the mesoderm layer
      4. The epiblast layer becomes known as the ectoderm
    • Ectoderm
      Skin, cornea and lens of eye, nervous system
    • Mesoderm
      Notochord, musculoskeletal, circulatory system
    • Endoderm
      Lining of GI tract, respiratory tract, urethra, bladder, reproductive system and liver and pancreas
    • Neurulation - week 3/4
      1. Mesoderm forms notochord
      2. Notochord stimulates ectoderm to thicken forming neural plate
      3. Neural plate forms 2 ridges which fuse to form neural tube
      4. Ectoderm layer forms over neural tube = outer skin of embryo
    • Craniofacial development external
      Week 4 - growth of ectomesenchyme cells leads to development of nasal placodes in the frontonasal processes
      Week 5 - nasal placodes invaginate backwards and medially to form nasal pits
      Week 5.5 and 6 - Medial sides of nasal pits fuse forming primary nasal septum and intermaxillary process
      Week 7 - Primary palate is also formed from the intermaxillary process
      Week 8 - Maxillary processes fuse with the lateral and medial nasal processes and the mandible
    • Craniofacial development - internal
      Weeks 7-8 - Palatine processes deflected downwards by developing tongue. The developing brain acquires a cervical flexure, lifting the head away from the cardiac bulge. This allows the tongue to drop into the floor of the mouth and the palatine shelves elevate
      Week 10 - All processes have grown to the point where they can make contact and fuse with each other, the primary palate and nasal septum
    See similar decks