n.
The middle embryonic germ layer, lying between the ectoderm and the endoderm, from which connective tissue, muscle, bone, and the urogenital and circulatory systems develop.
mesodermal mes'o·der'mal or mes'o·der'mic adj.
mesoderm
Dictionary:
mes·o·derm (mĕz'ə-dûrm', mĕs'-)  |
| 5min Related Video: mesoderm |
| Dental Dictionary: mesoderm |
n
The middle of the three cell layers of the developing embryo. It lies between the ectoderm and the endoderm. Bone, connective tissue, muscle, blood, vascular and lymphatic tissue, and the pleurae of the pericardium and peritoneum are all derived from the mesoderm.
| Columbia Encyclopedia: mesoderm |
mesoderm, in biology, middle layer of tissue formed in the gastrula stage of the developing embryo. At the end of the blastula stage, cells of the embryo are arranged in the form of a hollow ball. Continued cell movement results in an invagination of the bottom region of the embryo, producing a form that resembles a double-layered cup. A third layer, the mesoderm, is formed between the other two by growth of cells derived from a marginal zone. The mesoderm is the germ layer that forms many muscles, the circulatory and excretory systems, and the dermis, skeleton, and other supportive and connective tissue. It also gives rise to the notochord, a supporting structure between the neural canal and the primitive gut. In many animals, including vertebrates, the mesoderm surrounds a cavity known as the coelom, the space that contains the viscera. See embryo.
| Veterinary Dictionary: mesoderm |
The middle of the three primary germ layers of the embryo, lying between the ectoderm and entoderm; from it are derived the connective tissue, bone, cartilage, muscle, blood and blood vessels, lymphatics, lymphoid organs, notochord, pleura, pericardium, peritoneum, kidneys and gonads.
- extraembryonic m. — located outside the developing embryo and forming its accessory organs.
- paraxial m. — adjacent to the mid line beneath the epiblast of the embryo which develop into somites.
- somatic m. — the outer layer of the developing mesoderm.
- splanchnic m. — the inner layer of the developing mesoderm.
| Wikipedia: Mesoderm |
| Mesoderm | |
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| Organs derived from mesoderm. | |
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| Section through the embryo | |
| Gray's | subject #6 49 |
| Days | 16 |
| MeSH | Mesoderm |
In humans, the mesoderm is one of the three primary germ cell layers - the other two are the ectoderm and endoderm - in the very early embryo. The mesoderm is the middle layer. It differentiates to gives rise to a number of tissues and structures including bone, muscle, connective tissue, and the middle layer of the skin. Some cells in mesodermal tissues retain the capacity to differentiate in diverse directions. For example, some cells in the bone marrow (mesoderm) can become liver (endoderm).
More generally, the mesoderm is one of the three germ layers found in the embryos of animals more complex than cnidarians, making them triploblastic. Mesoderm forms in the embryo during gastrulation when some of the cells migrating inward to form the endoderm, produce an additional layer that lies between the endoderm and the ectoderm.
Mesoderm is found in all large, complex animals, and allows the formation of a coelom, which allows more room for independent growth of the body organs.
Contents |
Mesoderm Derivatives
General
The body organs, tissues and systems derived from the mesoderm in most triploblastic animals can be listed as follows:
- bones
- cartilage
- most of the circulatory system, including the heart and major blood vessels
- connective tissues of the gut and integuments
- mesenchyme
- mesothelium
- muscles
- peritoneum (lining of the abdominal cavity)
- reproductive system
- spleen
- urinary system, including the kidneys
Vertebrates
* Chordamesoderm: yellow, at the notochord. * Paraxial mesoderm: red, comprising the somites. * Intermediate mesoderm: purple, which includes the Wolffian duct. * Lateral plate mesoderm: purple, comprising somatic and splanchnic mesoderm.
Before formation of the items in the above list, the mesoderm of a developing vertebrate transitionally differentiates into the following sub-types:
- Chordamesoderm (also known as axial mesoderm) which later on gives rise to notochord in all chordates
- Paraxial mesoderm
- Intermediate mesoderm
- Lateral plate mesoderm
See also
References
 |
Look up mesoderm in Wiktionary, the free dictionary. |
- Evers, Christine A., Lisa Starr. Biology:Concepts and Applications. 6th ed. United States:Thomson, 2006. ISBN 0-534-46224-3.
External links
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 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more |
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| Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved. Read more |
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| Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/. Read more |
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| Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved. Read more |
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| Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Mesoderm". Read more |
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Mentioned in
- mesentoderm (embryology)
- mesodermal
- mesendoderm (embryology)
- mesodermal tumor (medicine)
- nephrotome (embryology)
- splanchnopleure
- cardiogenic plate (embryology)
- ectomesoderm (embryology)
- endocyst (invertebrate zoology)
- somatic mesoderm (embryology)
