Ectoderma: what is it and how it develops during pregnancy

The largest system or organ that makes up us, humans and animals, is the skin. This organ acts as a protective barrier for the whole organism and is made up of three main layers: the epidermis, the hypodermis and the hypodermis. The first of these, the epidermis (the outermost layer of the skin), begins its development from the embryonic period, from an earlier set of tissue called ectoderm.

In this article, we will see what the ectoderm is and is responsible for, as well as the precise moment of its development in which it originates.

    What is ectoderm?

    The ectoderm is the outer germ layer in the early embryo. It is one of the three germ layers of embryonic origin, found in both vertebrate and invertebrate animals. Basically, it is a set of cells that form the large tissues of our body, and which emerge from the first weeks of gestation.

    The ectoderm has been studied since 1817, when Christian Pander, a doctoral student at the University of Würzburg, Germany, discovered two embryonic plaques in vertebrates, which later led him to discover a third which was later called the ectoderm. Later, in 1825, Embryologist Martin Rathke discovered the same cell layers in invertebrate animals.

    Towards century XIX was Karl Ernst von Baer of the university of Konigsberg in Prusia, that extended these investigations and took them to different species. The same description of the blastula stage is attributed to the same researcher, which we will see developed later.

    How does it develop during pregnancy?

    During embryonic development, cells go through a multiple process of cell division. finally cells generated by this process reach a stage called gastrulation. It is in the latter that the embryo organizes three different germinal layers.

    One of these layers is the ectoderm. The others are the mesoderm and the endoderm. Together, the three layers that make up skin tissue, nerves, organs and muscles. They differ from each other in the depth to which they are found, as well as in their special functions.

    After gastrulation is complete, the embryo enters another stage known as neurulation, at which point the development of the nervous system begins. This stage is characterized by thickening of the ectoderm, which makes it possible to generate “neural plaques”. In turn, the neural plaques gradually thicken and feel the fundamentals of nervous system development.

    In other words, the central nervous system is formed from a first neural plate made up of ectodermal cells located on the dorsal surface of the embryo. This generates a neural tube which will later form the ventricles and cells necessary to strengthen the peripheral nervous system and the motor fibers that make it up. To better explain this process, the ectoderm has been divided into different parts.

      Parts of the ectoderm

      During the neurulation phase, the ectoderm is divided into two large parts: The superficial ectoderm and the neuroextoderm.

      1.superficial ectoderm

      The superficial ectoderm gives rise to the tissues found on the outermost surface of the body, For example the epidermis, hair or nails.

      2. Neuroectoderm

      In the neuroextoderm, it is in turn divided into two main elements, which will later shape the nervous system. One of them is the neural tube, the precursor to the central nervous system in the embryo, as well as the brain and spinal cord.

      The other is the neural crest, Which forms many bones and connective tissues in the head and face, as well as parts of the peripheral nervous system, such as certain nerve ganglia, as well as the adrenal glands and melanocytes (the ones that give rise to myelin).

      In other species, the ectoderm performs similar functions. Specifically in fish, the neural crest forms the spine and in turtles it helps form the shell.

      its functions

      As we have seen, the ectoderm this is the layer from which the skin and all sensitive structures derive. Being a layer, it is made up of groups of cells that fuse with each other during the embryonic development of all animals. In vertebrate animals, the ectoderm is responsible for the development of the following tissues:

      • skin
      • fingernails
      • Eye lens
      • epitheliumIn other words, the tissue that covers the organs that regulate the senses.
      • Scalp and hair
      • nasal cavity
      • paranasal sinuses
      • Mouth, including tooth enamel
      • anal canal
      • nerve tissue, Including endocrine cells such as the pituitary body and chromaffin tissue

      In contrast, in invertebrate animals such as cnidarians or ctenophores (relatively simple aquatic animals of the taxonomic category “sections”), the ectoderm covers the whole body, so in these cases the epidermis and ectoderm are the same. layer.

      Bibliographical references:

      • Ectoderm (2018). Encyclopedia Britannica. Retrieved August 22. Available at https://www.britannica.com/science/ectoderm.
      • MacCord, K. (2013). Ectoderm. The Embryo Project Encyclopedia. Accessed August 22, 2018.Available at https://embryo.asu.edu/pages/ectoderm.
      • Martos, C. (2018). Ectoderm: parts, derivatives and alterations. Lifeder.com. Accessed August 22, 2018.Available at https://www.lifeder.com/ectodermo/.
      • Poch, ML (2001). Neurobiology of early development. Educational contexts, 4: 79-94.

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