Definition of ectoderm in English:



mass nounZoology Embryology
  • The outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis, nerve tissue, and nephridia.

    • ‘The presumptive neural tube tissues consist of a layer of ectoderm along the dorsal midline of the embryo, between the notochord and an outer layer of epidermis.’
    • ‘The branchial arches begin as cylindrical cores of mesenchyme sandwiched between continuous sheets of epidermal ectoderm and internal endoderm.’
    • ‘The anthozoans are diploblastic animals developing from two epithelial germ cell layers: the ectoderm, facing the seawater, and the endoderm, facing the gastrovascular cavity or coelenteron.’
    • ‘At a tissue level, an adult hydra is essentially a tube composed of two tissue layers, the ectoderm and the endoderm, which extend throughout the animal.’
    • ‘It is involved in mesoderm development and differentiation of the neural ectoderm into epidermoblasts and neuroblasts.’


Mid 19th century from ecto-‘outside’ + Greek derma ‘skin’.