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2.2: Germ layers

  • Page ID
    42906
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    Specification

    Following fertilization and cleavage, the mass of cells must become specified to each of the types of cells needed to form the whole organism. 

    A summary of mechanisms that can be used to specify cells can be found in the section, The Developmental Mechanics of Cell Specification, from Gilbert's Developmental Biology https://www.ncbi.nlm.nih.gov/books/NBK9968/.

     

    Gastrulation and the formation of germ layers

    After cleavage forms a group of cells, the cells undergo a series of movements to establish the correct cells in the correct positions and establish a basic animal body plan.

    Video \(\PageIndex{1}\): Animal Development: We're Just Tubes. Hank discusses the process by which organisms grow and develop, maintaining that, in the end, we're all just tubes. (Copyright - Crash Course Biology via YouTube)

     

    In most animals three germ layers are established after fertilization and specification. Endoderm cells will produce the digestive system and its associated organs like pancreas and liver, as well as lungs. Mesodermal cells are the source of many internal organs such as heart, muscle, kidney, somatic gonad, and blood. Ectodermal cells will form two major groups of cells, the epidermal ectoderm (skin) and the neural ectoderm (brain and central nervous system). 

    File:Germ layers.jpg
    Figure \(\PageIndex{1}\): Examples of cells derived from endoderm, mesoderm, and ectoderm. (Copyright CC-BY CNX via https://commons.wikimedia.org/wiki/F...erm_layers.jpg)

     


    2.2: Germ layers is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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