agenesis
American Heritage Dictionary:
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a·gen·e·sis
(ā-jĕn'ĭ-sĭs) 
n.
Absence or incomplete development of an organ or body part.
n.
Absence or incomplete development of an organ or body part.
Britannica Concise Encyclopedia:
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agenesis
Failure of all or part of an organ to develop during embryonic growth. Many forms of agenesis are lethal, such as absence of the entire brain (anencephaly), but agenesis of one organ of a pair may cause little problem. Agenesis of a kidney, bladder, testicle, ovary, thyroid, and lung are known. Agenesis of the arms or legs is called meromelia (absence of one or both hands or feet), phocomelia (normal hands and feet but no arms or legs), and amelia (complete absence of a limb or limbs). Agenesis may be caused by absence of embryonic tissue or by chemical exposure in the uterus, and it is often associated with other congenital disorders.
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Saunders Veterinary Dictionary:
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agenesis
Absence of an organ due to nonappearance of its primordium in the embryo.
Mosby's Dental Dictionary:
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agenesis
(ājen′əsis)
n
n
The defective development or congenital absence of parts.
Wikipedia on Answers.com:
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Agenesis
In medicine, agenesis refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue. Many forms of agenesis are referred to by individual names, depending on the organ affected:
- Agenesis of the corpus callosum- failure of the Corpus callosum to develop
- Renal agenesis- failure of one or both of the kidneys to develop
- Phocomelia- failure of the arms or legs to develop
- Penile agenesis- failure of penis to develop
- Müllerian agenesis - failure of the uterus and part of the vagina to develop
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Contents
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Eye agenesis
Eye agenesis is a medical condition in which sufferers are born with no eyes.
Dental & oral agenesis
Ear agenesis
Ear agenesis is a medical condition in which people are born without ears.
Because the middle and inner ears are necessary for hearing, people with complete agenesis of the ears suffer from total deafness. Minor agenesis that affects only the visible parts of the outer ear, which may be called microtia, typically produces cosmetic concerns and perhaps hearing impairment if the opening to the ear canal is blocked, but not deafness.
References
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Copyrights:
American Heritage 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.
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Britannica Concise Encyclopedia
Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved. Read more
Saunders 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.
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Mosby's Dental Dictionary
Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.
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