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1, 2 and 3 syllabus points - Coggle Diagram

- - - - ovum+sperm in fallopian tube= zygote 140um
        
        zygote divides 2>4>8 cell
        
        morula (10-32 cells)
        
        blastocyst-cell differentiation, cavitation
    - - 2 cavities form on either side of the inner cell mass- in the middle is the disc
        
        1) sac lined with ectodermal cells
        
        amniotic cavity
        
        2) lined with endodermal cells
        
        yolk sac
      - bilaminar disc
        
        upper: epiblast > ectoderm, mesoderm, endoderm
        
        lower: hypoblast > extraembryonic endoderm
  - - - 1- notochord formation (it organises whole embryo)
      - 2-pharyngeal membrane formation (primary mouth)
      - 3- neural plate formation (incentive for formation of all organs)
    - - by mesoderm cells deep inside primitive node
      - ectoderm cells > differentiate into neuroectoderm cells
      - neural plate is made from neuroectoderm cells (because of signals from the notochord boss)
        
        neural plate thickents, and invaginates> in the center= neural groove
        
        groove deepens and two folds on either side = neural folds
        
        neural folds develop neural crest cells
      - mesoderm can form
        
        the notochord
        
        38 somite pairs
        
        spine, trunk neck head etc
    - - closure of the neural tube by folding, ectoderm rejoins, neural crest cells rejoins, notochord degenerates. Neuroectoderm (neural crest cells) layer forms PNS. Neural crest cells in HEAD area help form ectomesenchyme- connective tissue.
      - mesoderm forms mesenchyme which is connective tissue of the rest of the body
      - ALL TISSUES OF THE TOOTH FORMED BY NEURAL CREST CELLS (except enamel)
      - neural tube 3 parts
        
        pars cranialis> head + brain
        
        prosencephalon
        
        mesencephalon
        
        rhombencephalon
        
        pars umbilicalis> forms torso with organs
        
        pars caudalis> forms limbs
- - - - THESE CELLS DISINTEGRATE LEAVING AN OPENING CALLED THE STOMODEUM
- - - - HOW DOES SECONDARY PALATE CLOSE? HARDENING OF PALATINE SHELVES.
- - - - INTRAMEMBRANOUS OSSIFICATION 7W- forms bone anterioroly and posteriorly along the cartilage rod. Symphysis (chin) fuses after birth
        
        mandibular ramus forms posteriorly (backwards towards the pharyngeal arches)