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Sperm in the Female Tract - Anatomy & Physiology (view source)
Revision as of 08:06, 8 September 2008
, 08:06, 8 September 2008→Capacitation
== Capacitation==
== Capacitation==
* If semen is deposited in the cranial vagina, capacitation may begin as sperm ascend the cervix.
* If semen is deposited in the caudal cervix (mare) or mid-cervix (sow) and immediately enters the uterus, capacitation is initiated in the uterus and completed in the isthmus of the oviduct.
* During Capacitation, the plasma membrane of the sperm undergoes marked biochemical changes.
* During mixing of sperm with seminal plasma, epididymal sperm become coated in seminal plasma proteins. These are stripped by the female tract environment. These proteins were the decapacitating agents that were rendering the sperm incapable of fertilization.
* Once the plasma proteins have been stripped, the portions of molecules that can bind to the zona pellucida of the oocyte are exposed.
* Membrane lipases and protein kinases destabilize the plasma membrane, enabling it to undergo fusion if it is brought close to another membrane (it is said to become 'fusogenic').
* Normally, intracellular calcium levels are low. Entry of calcium ions causes a sharp rise in intracellular calcium that signals for the acrosome reaction to occur.
* Sperm remain in the female tract awaiting fertilization by an ovulated oocyte, this can be:
** ~24 hours in a cow
** ~40 hours in a sheep
** ~7/8 days in a bitch
* Sperm are a heterogenous population, so they are not all capacitated at the same rate.
== Privileged Pathways ==
== Privileged Pathways ==