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ectoderm
ectoderm layer of cells that covers the surface of an animal embryo after the process of gastrulation has occurred. This outer layer, together with the endoderm , or inner layer, is present in all early embryos. In the development of animals of the phyla Porifera , Ctenophora , and Cnidaria , these two primary layers give rise to all the tissues and organs of the animals, a process known as diploblastic development. In higher animals, such as those of the phyla Echinodermata and Chordata , a third, middle layer, the mesoderm , is formed between the ectoderm and endoderm during gastrulation, and the process is termed triploblastic development. In most embryos, differentiation of ectodermal tissue gives rise to epidermis and its specialized structures (scales, feathers, nails, and hair); some exocrine glands (sweat and sebaceous glands); some endocrine glands (the pineal body and the pituitary gland); the nervous system; and the organs of special sense (ear and eye). In animals of some phyla, such as the Mollusca and Annelida , the fate of particular cells of the embryo is determined in the earliest stages of the fertilized egg and may even be fixed at or before fertilization. |
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"ectoderm." The Columbia Encyclopedia, 6th ed.. 2008. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "ectoderm." The Columbia Encyclopedia, 6th ed.. 2008. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1E1-ectoderm.html "ectoderm." The Columbia Encyclopedia, 6th ed.. 2008. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-ectoderm.html |
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ectoderm
ec·to·derm / ˈektəˌdərm/ • n. Zool. & 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. Compare with endoderm and mesoderm. DERIVATIVES: ec·to·der·mal / ˌektōˈdərməl/ adj. |
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"ectoderm." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "ectoderm." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O999-ectoderm.html "ectoderm." The Oxford Pocket Dictionary of Current English. 2009. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-ectoderm.html |
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ectoderm
ectoderm (ek-toh-derm) n. the outer of the three germ layers of the early embryo. It gives rise to the nervous system and sense organs, the teeth and lining of the mouth, and the epidermis and its associated structures (hair, nails, etc.).
—ectodermal adj. |
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"ectoderm." A Dictionary of Nursing. 2008. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "ectoderm." A Dictionary of Nursing. 2008. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O62-ectoderm.html "ectoderm." A Dictionary of Nursing. 2008. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O62-ectoderm.html |
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ectoderm
ectoderm In a triploblastic embryo, the outer layer of cells which eventually give rise to the epidermis, the most anterior and posterior portions of the digestive tract, and the majority of the nervous system.
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MICHAEL ALLABY. "ectoderm." A Dictionary of Zoology. 1999. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "ectoderm." A Dictionary of Zoology. 1999. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O8-ectoderm.html MICHAEL ALLABY. "ectoderm." A Dictionary of Zoology. 1999. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-ectoderm.html |
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ectoderm
ectoderm The external layer of cells of the gastrula, which will develop into the epidermis and the nervous system in the adult. See also germ layers.
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"ectoderm." A Dictionary of Biology. 2004. Encyclopedia.com. 11 Feb. 2012 <http://www.encyclopedia.com>. "ectoderm." A Dictionary of Biology. 2004. Encyclopedia.com. (February 11, 2012). http://www.encyclopedia.com/doc/1O6-ectoderm.html "ectoderm." A Dictionary of Biology. 2004. Retrieved February 11, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-ectoderm.html |
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