Capacitation
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/* Discovery */
:''This article is about a biological process related to reproduction; for the other use, see [[Capacitation (NGO)]].''
'''Capacitation''' is the penultimate<ref>Essential Reproduction, Johnson, 6th edition, Blackwell Publishing</ref> step in the maturation of [[Mammal|mammalian]] [[Spermatozoon|spermatozoa]] and is required to render them competent to [[Fertilization|fertilize]] an [[oocyte]].
This step is a biochemical event; the sperm move normally and look mature prior to capacitation.
''[[Wiktionary:In vivo|In vivo]]'' this step typically occurs after [[ejaculation]], in the female [[Sex organ|reproductive tract]].
''[[Wiktionary:In vitro|In vitro]]'', capacitation can occur in sperm that have either undergone ejaculation or have been extracted from the [[epididymis]].
By secreting sterol binding albumin, lipoproteins, proteolytic and glycosidasic [[enzymes]] such as heparin, the [[uterus]] aids in the steps of capacitation.
Non-mammalian spermatozoa do not require this capacitation step and are ready to fertilize an oocyte immediately after release from the male. After this capacitation the sperm must undergo activation involving the [[acrosome reaction]].
==Result of capacitation==
Capacitation involves the destabilisation of the sperm head membrane rendering it more fusigenic. This change is facilitated by the removal of [[sterols]] (e.g. [[cholesterol]]) and non-covalently bound epididymal/seminal [[glycoproteins]]. The result is a more fluid membrane with an increased permiability to Ca<sup>2+</sup>.
An influx of Ca<sup>2+</sup> produces increased intracellular [[cAMP]] levels and thus, an increase in motility. [[Hyperactivation]] is also part of capacitation and is the result of the increased Ca<sup>2+</sup> levels. The enzyme FPP (fertilization promoting factor) produced by the male is essential for capacitation.
==Discovery==
The discovery of this process was independently reported in 1951 by both [[Min Chueh Chang]]<ref>Chang, M. C. (1951) “Fertilizing capacity of spermatozoa deposited into the fallopian tubes,” ''Nature'', vol. 168, pages 697-698.</ref> and [[Colin Russell Austin]]<ref>Austin, C. R. (1951) “Observations of the penetration of sperm into the mammalian egg,” ''Australian Journal of Scientific Research'', Series B, vol. 4, pages 581-596.</ref> <ref>Austin, Colin Russell: obituary: “Colin Austin,” ''Australian Academy of Science Newsletter'', No. 60, page 11 (August-November 2004). Available on-line at: http://www.science.org.au/newsletters/aas60.pdf .</ref>.
Historically, the term "capacitation" has evolved in meaning and this should be taken into account when consulting sources.
==See also==
*[[Cortical reaction]]
*[[Acrosome reaction]]
==Footnotes==
{{reflist}}
==References==
* Beaudin, Stacey; Kipta, Donna; and Orr, Annamarie. (October 9, 1996). [http://www.ucalgary.ca/UofC/eduweb/virtualembryo/capacitation.html Current research into sperm capacitation: An Essay on Visconti, et al. Development 121: 1129-1150 (1995)]. Verified availability 2005-04-06.
* Visconti, Pablo E.; Bailey, Janice L.; Moore, Grace D.; Pan, Dieyun; Olds-Clarke, Patricia; and Kopf, Gregory S. (1995). Capacitation of mouse spermatozoa: I. Correlation between the capacitation state and protein tyrosine phosphorylation. ''Development'' '''121''', 1129-1137. PMID 7743926. <small>full article text available on-line</small>
==External links==
* {{MeshName|Sperm+Capacitation}}
[[Category:Reproductive system]]
[[Category:Germ cells]]
[[Category:Andrology]]
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