ectoderm

Examples of ectoderm in the following topics:

• Organogenesis

  • For example, some cells in the ectoderm will express the genes specific to skin cells.
  • The ectoderm forms epithelial cells and tissues, as well as neuronal tissues.
  • During the formation of the neural system, special signaling molecules called growth factors signal some cells at the edge of the ectoderm to become epidermis cells.
  • If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue.
  • The central region of the ectoderm forms the neural tube, which gives rise to the brain and the spinal cord.

• Gene Expression for Spatial Positioning

  • For example, some cells in the ectoderm (the outer tissue layer of the embryo) will express the genes specific to skin cells.
  • The ectoderm forms epithelial cells and tissues, as well as neuronal tissues.
  • During the formation of the neural system, special signaling molecules called growth factors signal some cells at the edge of the ectoderm to become epidermis cells.
  • If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue.
  • The central region of the ectoderm forms the neural tube, which gives rise to the brain and the spinal cord.

• Animal Characterization Based on Features of Embryological Development

  • Radially-symmetrical animals are diploblasts, developing two germ layers: an inner layer (endoderm) and an outer layer (ectoderm).
  • Diploblasts have a non-living layer between the endoderm and ectoderm.
  • The ectoderm develops into the outer epithelial covering of the body surface and the central nervous system.
  • During embryogenesis, diploblasts develop two embryonic germ layers: an ectoderm and an endoderm.
  • Triploblasts develop a third layer, the mesoderm, between the endoderm and ectoderm

• Cleavage, the Blastula Stage, and Gastrulation

  • The three germs layers are the endoderm, the ectoderm, and the mesoderm.
  • The ectoderm gives rise to the nervous system and the epidermis; the mesoderm gives rise to the muscle cells and connective tissue in the body; and the endoderm gives rise to columnar cells found in the digestive system and many internal organs.
  • The three germ layers give rise to different cell types in the animal body: the ectoderm forms the nervous system and the outer layer of skin, the mesoderm gives rise to muscles and connective tissues, and the endoderm gives rise to the lining of the digestive system and other internal organs.

• Superphylum Lophotrochozoa

  • Animals belonging to superphylum Lophotrochozoa are protostomes: the blastopore (or the point of involution of the ectoderm or outer germ layer) becomes the mouth opening to the alimentary canal.
  • The lophotrochozoans are triploblastic, possessing an embryonic mesoderm sandwiched between the ectoderm and endoderm found in the diploblastic cnidarians.

• Establishing Body Axes during Development

  • The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into a closed tube, the neural tube or neural canal, the ectodermal wall of which forms the rudiment of the nervous system .
  • Primary neurulation divides the ectoderm into three cell types: the internally located neural tube, the externally located epidermis, and the neural crest cells, which develop in the region between the neural tube and epidermis but then migrate to new locations.
  • In the head, neural crest cells migrate, the neural tube closes, and the overlying ectoderm closes.
  • In the trunk, overlying ectoderm closes, the neural tube closes and neural crest cells migrate.
  • The central region of the ectoderm forms the neural tube, which gives rise to the brain and the spinal cord.

• Cellular Differentiation

  • A pathway that is guided by the cell adhesion molecules is created as the cellular blastomere differentiates from the single-layered blastula to the three primary layers of germ cells in mammals, namely the ectoderm, mesoderm and endoderm (listed from most distal, or exterior, to the most proximal, or interior).
  • The ectoderm ends up forming the skin and the nervous system, the mesoderm forms the bones and muscular tissue, and the endoderm forms the internal organ tissues.

• Phylum Cnidaria

  • All cnidarians show the presence of two membrane layers in the body that are derived from the endoderm and ectoderm of the embryo.
  • The outer layer (from ectoderm) is called the epidermis and lines the outside of the animal, whereas the inner layer (from endoderm) is called the gastrodermis and lines the digestive cavity.

• Class Anthozoa

  • Each mesentery consists of one ectodermal and one endodermal cell layer with the mesoglea sandwiched in between.

• Phylum Chordata

  • A dorsal nerve cord which develops from a plate of ectoderm that rolls into a tube located dorsal to the notochord.