acrosome
American Heritage Dictionary:
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ac·ro·some
Oxford Dictionary of Biochemistry:
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acrosome
a modified lysosome in the head of a spermatozoon that contains acid hydrolases concerned in the breakdown of the outer membrane of the ovum during fertilization. It lies anterior to the nucleus just beneath the plasma membrane. See also acrosin.
| acrosomal process, acrosin, acromegaly | |
| acrylamide, actin, actin filament |
Saunders Veterinary Dictionary:
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acrosome
The caplike, membrane-bounded structure that covers the anterior portion of the head of the mammalian spermatozoon; it is bounded by an inner and an outer membrane and contains enzymes involved in penetration of the ovum.
- a. reaction — fusion of the outer acrosomal membrane with the sperm plasma membrane, and the breakdown of the fused complex, after the attachment of the spermatozoon to the zona pellucida. It is induced by substances from the egg investments and releases enzymes involved in penetration of the ovum.
Wikipedia on Answers.com:
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Acrosome
The acrosome is an organelle that develops over the anterior half of the head in the spermatozoa (sperm cells) of many animals. It is a cap-like structure derived from the Golgi apparatus. Acrosome formation is completed during testicular maturation. In Eutherian mammals the acrosome contains digestive enzymes (including hyaluronidase and acrosin).[1] These enzymes break down the outer membrane of the ovum, called the zona pellucida, allowing the haploid nucleus in the sperm cell to join with the haploid nucleus in the ovum.
This shedding of the acrosome or acrosome reaction can be stimulated in vitro by substances a sperm cell may encounter naturally such as progesterone or follicular fluid, as well as the more commonly used calcium ionophore A23187. This can be done to serve as a positive control when assessing the acrosome reaction of a sperm sample by flow cytometry [2] or fluorescence microscopy. This is usually done after staining with a fluoresceinated lectin such as FITC-PNA, FITC-PSA, FITC-ConA, or fluoresceinated antibody such as FITC-CD46.[3]
In the case of globozoospermia (sperm with round heads), the Golgi apparatus is not transformed into the acrosome, causing male infertility.[4]
References
- ^ "acrosome definition - Dictionary - MSN Encarta". Archived from the original on 2009-10-31. http://www.webcitation.org/5kwDPQanq. Retrieved 2007-08-15.
- ^ Miyazaki et al. Archives of Andrology 25:243-251 (1990)
- ^ Carver-Ward et al. Journal of Assisted Reproduction and Genetics, Vol. 14, no. 2, 1997
- ^ Page 155 in: Hermann Behre; Eberhard Nieschlag (2000). Andrology : Male Reproductive Health and Dysfunction. Berlin: Springer. ISBN 3-540-67224-9.
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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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Oxford Dictionary of Biochemistry
Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.
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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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