Changes

The [[Female_Reproductive_Tract_-The_Uterus_-_Anatomy_%26_Physiology|uterus]] is an important site of prostaglandin synthesis.  During pregnancy, the presence of the foetus inhibits the production of prostaglandins in order to prevent luteolysis.  At parturition, an increase in prostaglandin synthesis is required.

The [[Female_Reproductive_Tract_-The_Uterus_- Anatomy & Physiology|uterus]] is an important site of prostaglandin synthesis.  During pregnancy, the presence of the foetus inhibits the production of prostaglandins in order to prevent luteolysis.  At parturition, an increase in prostaglandin synthesis is required.

* Prostaglandins are synthesized from '''arachadonic acid''', which is derived from '''glycerophospholipids''' by the enzyme '''phospholipase A2''' (PLA2).

* Prostaglandins are synthesized from '''arachadonic acid''', which is derived from '''glycerophospholipids''' by the enzyme '''phospholipase A2''' (PLA2).

[[Image:Parturition Cascade.jpg|thumb|right|150px|The Parturition Cascade, Copyright RVC 2008]]

[[Image:Parturition Cascade.jpg|thumb|right|150px|The Parturition Cascade, Copyright RVC 2008]]

Details of Oxytocin Synthesis and Secretion may be found [[Pituitary_Gland_-_Anatomy_%26_Physiology#Oxytocin|here]].

Details of Oxytocin Synthesis and Secretion may be found [[Pituitary_Gland_- Anatomy & Physiology#Oxytocin|here]].

* Oxytocin acts to:  

* Oxytocin acts to:  

** Increase [[Parturition_-_Coordinated_Myometrial_Contraction_-_Anatomy_%26_Physiology|myometrial contraction]] (positive feedback)

** Increase [[Parturition_-_Coordinated_Myometrial_Contraction_- Anatomy & Physiology|myometrial contraction]] (positive feedback)

** Increase Prostaglandin release

** Increase Prostaglandin release

* Produced by either the corpus luteum or placenta depending on species.

* Produced by either the corpus luteum or placenta depending on species.

* Synthesis is stimulated by '''PGF2α'''

* Synthesis is stimulated by '''PGF2α'''

* Causes softening of the connective tissue in the [[Female_Reproductive_Tract_-The_Cervix_-_Anatomy_%26_Physiology|cervix]].

* Causes softening of the connective tissue in the [[Female_Reproductive_Tract_-The_Cervix_- Anatomy & Physiology|cervix]].

* Promotes elasticity of pelvic ligaments.

* Promotes elasticity of pelvic ligaments.

* Prepares the birth canal by loosening supportive tissues so that the passage of the foetus can occur with relative ease.

* Prepares the birth canal by loosening supportive tissues so that the passage of the foetus can occur with relative ease.

== Role of Oestrodiol Elevation prior to Parturition ==

== Role of Oestrodiol Elevation prior to Parturition ==

* Initiates secretory activity of the reproductive trace, particularly the [[Female_Reproductive_Tract_-The_Cervix_-_Anatomy_%26_Physiology|cervix]].

* Initiates secretory activity of the reproductive trace, particularly the [[Female_Reproductive_Tract_-The_Cervix_- Anatomy & Physiology|cervix]].

* Causes the [[Female_Reproductive_Tract_-The_Cervix_-_Anatomy_%26_Physiology|cervix]] and [[Reproductive_Tract_-The_Vagina/Vestibule_-_Anatomy_%26_Physiology|vagina]] to produce mucus.

* Causes the [[Female_Reproductive_Tract_-The_Cervix_- Anatomy & Physiology|cervix]] and [[Reproductive_Tract_-The_Vagina/Vestibule_- Anatomy & Physiology|vagina]] to produce mucus.

** Washes out the cervical seal of pregnancy.

** Washes out the cervical seal of pregnancy.

** Lubricates the cervical canal and vagina

** Lubricates the cervical canal and vagina

* The foetus initiates parturition.

* The foetus initiates parturition.

* For parturition to occur, progesterone production by the corpus luteum must be terminated.

* For parturition to occur, progesterone production by the corpus luteum must be terminated.

* As the foetus grows in a restrictive environment it becomes stressed.  Stress leads to a rise in foetal [[Pituitary_Gland_-_Anatomy_%26_Physiology#Hormones_of_the_Anterior_Pituitary_Gland|ACTH]].  The rise in ACTH causes production of Cortisol from the foetal [[Adrenal_Glands_-_Anatomy_%26_Physiology|adrenal Glands]].

* As the foetus grows in a restrictive environment it becomes stressed.  Stress leads to a rise in foetal [[Pituitary_Gland_- Anatomy & Physiology#Hormones_of_the_Anterior_Pituitary_Gland|ACTH]].  The rise in ACTH causes production of Cortisol from the foetal [[Adrenal_Glands_- Anatomy & Physiology|adrenal Glands]].

* The rise in foetal cortisol leased to an increased oestrogen:progesterone ratio by upregulating '''aromatase''' enzymes which convert androgens to oestrogens.  Cortisol also reduces progesterone production.

* The rise in foetal cortisol leased to an increased oestrogen:progesterone ratio by upregulating '''aromatase''' enzymes which convert androgens to oestrogens.  Cortisol also reduces progesterone production.