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Embryonic Development (Weeks 3-8) definitions

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  • Gastrulation
    Transformation of the bilaminar embryonic disc into a trilaminar disc with three germ layers.
  • Endoderm
    Inner germ layer forming the epithelial lining of the digestive, respiratory, and urogenital systems.
  • Mesoderm
    Middle germ layer forming structures like the notochord, somites, and cardiovascular system.
  • Ectoderm
    Outer germ layer developing into the nervous system, sense organs, and epidermis.
  • Primitive streak
    A groove on the embryonic disc facilitating the formation of the three germ layers.
  • Organogenesis
    Process where germ layers differentiate into organs and systems, recognizable by week 8.
  • Notochord
    Structure formed by mesodermal cells, organizing the embryo along a central axis.
  • Somites
    Paired structures from mesoderm developing into the skeleton, dermis, and skeletal muscle.
  • Neurulation
    First major event of ectoderm specialization forming the nervous system.
  • Neural plate
    Thickened ectoderm portion that folds to form the neural tube.
  • Neural tube
    Structure formed from the neural plate, developing into the central nervous system.
  • Neural crest cells
    Cells forming between ectoderm and neural tube, creating peripheral nervous system structures.
  • Yolk sac
    Structure attached to the endoderm, evolving throughout development.
  • Alantois
    Structure developing into a portion of the urinary bladder.
  • Epidermis
    Outer skin layer formed by the ectoderm, covering the body.