Embryonic Development

Embryonic Development

1. Oocyte

   • Zygote (post-fertilization)
     • Morula (Day 4) (16-32 cells)
       • Blastocyst
         • Embryoblast (inner)
           • Bilaminar Disc
             • Epiblast
             • Hypoblast
             • Trilaminar Disc (through Gastrulation)
               • Ectoderm "Outside"
                 • Epidermis, NS, Retina
               • Mesoderm
                 • Muscles, CT, Bone, Dermis
                 • Paraxial (somites)
                   • Sclerotome
                     • Vertebrae/ribs
                   • Myotome
                     • Dorsal mass (epimere)
                       • Epaxial muscles (Intrinsic back)
                         • Innvervated by dorsal primary rami
                     • Ventral mass (hypomere)
                       • Hypaxial muscles (trunk muscles)
                         • Innvervated by ventral primary rami
                   • Dermatome
                     • Dermis layer/nerve
                 • Intermediate (UG tract)
                 • Lateral (body walls)
                   • Somatopleura
                     • Body walls
                   • Splanchnopleura
                     • Gut wall
                   • Intra-embryonic coelom
                     • Body cavities
                 • Notochord
                   • Signals ectoderm to begin neurulation
               • Endoderm
                 • Epithelial lining of respiratory and GI systems
         • Trophoblast (outer)
           • Syncytiotrophoblast
           • Cytotrophoblast