Difference between revisions of "Normal Parturition - Anatomy & Physiology"

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<big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big>
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==Stages of Parturition==
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<big><center>[[Reproductive_System#Parturition|'''BACK TO PARTURITION''']]</center></big>
  
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*Stage 1: this is the preparatory stage, starting at the onset of regular uterine contractions followed by cervical dilatation and the foetus assuming the correct disposition for passage through the birth canal.
 
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*Stage 2: the expulsive stage, characterised by the onset of abdominal contractions which together with uterine contractions lead to foetal expulsion
 
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*Stage 3: separation and expulsion of the foetal membranes. In polycotous species second and third stages are often inter-mixed.
 
  
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The following table summarises the normal time taken to progress through the stages of parturition in different species.
 
 
{| style="width:75%; height:200px" border="1"
 
{| style="width:75%; height:200px" border="1"
  
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| '''Stage 2: Foetal Expulsion'''
 
| '''Stage 2: Foetal Expulsion'''
 
| 12-30 minutes
 
| 12-30 minutes
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| 30 minutes - 4 hours
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| 30-60 minutes
 
| 30-120 minutes
 
| 30-120 minutes
 
| 150-180 minutes
 
| 150-180 minutes
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The step in the reproductive process that immediately precedes lactation, uterine involution and return to cyclicity.  It is initiated by the foetus and involves a complex cascade of endocrine events. Parturition is the process by which the conceptus (foetus, placenta and placental membranes) is expelled from the [[Uterus - Anatomy & Physiology|uterus]]; this requires [[Cervical Softening - Anatomy & Physiology|cervical softening]],[[Uterine Contraction - Anatomy & Physiology|coordinated myometrial contractions]] and contraction of abdominal muscles
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to occur
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Parturition is the Process by which the conceptus (foetus, placenta and placental membranes) are expelled from the [[Female_Reproductive_Tract_-The_Uterus_-_Anatomy_%26_Physiology|Uterus]] requires:
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* [[Parturition - Cervical Softening - Anatomy & Physiology|Cervical Softening]]
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* [[Parturition - Coordinated Myometrial Contraction - Anatomy & Physiology|Coordinated Myometrial Contraction]]
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* Voluntary contraction of abdominal muscles
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= Stage 3: Placental Expulsion =
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In most species, expulsion of foetal membranes quickly follows expulsion of the foetus. 
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* After the birth of the young, regular abdominal contractions largely cease.
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* Myometrial contractions persist.
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** Decreased amplitude, but become more frequent and less regular.
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** Important for dehiscence and expulsion of foetal membranes.
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* Waves of contractions from uterus to the cervix persist.
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** Act in a peristaltic fashion in the cow and sow in the reverse direction.
  
 
== Placental Changes ==
 
== Placental Changes ==
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* Open endometrial crypts
 
* Open endometrial crypts
 
* Foetal villi have shrunk due to the escape of blood from the foetal side of the placenta when the umbillical cord ruptures.
 
* Foetal villi have shrunk due to the escape of blood from the foetal side of the placenta when the umbillical cord ruptures.
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* [[Uterine Contraction - Anatomy & Physiology|Myometrial contractions]] aid exsanguination of the placenta.
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* Myometrial contractions aid exsanguination of the placenta.
 
* Separation of foetal membranes.
 
* Separation of foetal membranes.
 
* Apex of the allantochorionic sac becomes inverted.
 
* Apex of the allantochorionic sac becomes inverted.
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** Not the mare or camelids.
 
** Not the mare or camelids.
  
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== Placental Expulsion ==
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= Parturition Behaviour =
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== Mare ==
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=== Stage 1 ===
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=== Stage 2 ===
  
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In most species, expulsion of foetal membranes quickly follows expulsion of the foetus. 
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=== Stage 3 ===
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== Cow ==
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=== Stage 1 ===
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=== Stage 2 ===
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=== Stage 3 ===
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== Ewe ==
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== Sow ==
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=== Stage 1 ===
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=== Stage 2 ===
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=== Stage 3 ===
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== Bitch ==
  
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* After the birth of the young, regular abdominal contractions largely cease.
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=== Stage 1 ===
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* Myometrial contractions persist.
 
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** Decreased amplitude, but become more frequent and less regular.
 
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** Important for dehiscence and expulsion of foetal membranes.
 
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* Waves of contractions from uterus to the cervix persist.
 
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** Act in a peristaltic fashion in the cow and sow in the reverse direction.
 
  
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=== Stage 2 ===
  
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== Parturition Behaviour ==
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=== Stage 3 ===
  
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=== [[Parturition Behaviour - Mare|Mare]] ===
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== Cat ==
  
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===[[Parturition Behaviour - Cow| Cow]] ===
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=== Stage 1 ===
  
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===[[Parturition Behaviour - Ewe| Ewe]] ===
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=== Stage 2 ===
  
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===[[Parturition Behaviour - Sow| Sow]] ===
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=== Stage 3 ===
  
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===[[Parturition Behaviour - Bitch| Bitch]] ===
 
  
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===[[Parturition Behaviour - Cat| Cat]] ===
 
  
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<big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big>
  
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{{OpenPages}}
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<big><center>[[Reproductive_System#Parturition|'''BACK TO PARTURITION''']]</center></big>
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[[Category:Parturition]]
 
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[[Category:Bullet Points]]
 

Revision as of 09:59, 4 August 2008

BACK TO REPRODUCTIVE SYSTEM
BACK TO PARTURITION


Species Mare Cow Ewe Sow Bitch
Stage 1: Contractions and Cervical Dilation 1-4 hours 2-6 hours 2-6 hours 2-12 hours 6-12 hours
Stage 2: Foetal Expulsion 12-30 minutes 30-60 minutes 30-120 minutes 150-180 minutes 6 hours (up to 24 hours with large litters)
Stage 3: Placental Expulsion 1 hour 6-12 hours 5-8 hours 1-4 hours Placenta Exits with Foetus



Parturition is the Process by which the conceptus (foetus, placenta and placental membranes) are expelled from the Uterus requires:


Stage 3: Placental Expulsion

In most species, expulsion of foetal membranes quickly follows expulsion of the foetus.

  • After the birth of the young, regular abdominal contractions largely cease.
  • Myometrial contractions persist.
    • Decreased amplitude, but become more frequent and less regular.
    • Important for dehiscence and expulsion of foetal membranes.
  • Waves of contractions from uterus to the cervix persist.
    • Act in a peristaltic fashion in the cow and sow in the reverse direction.

Placental Changes

During the last 5 days of gestation, there are changes in the placenta.

  • Collaginisation of the placentome.
  • Flattening of maternal crypt epithelium.
  • Leucocyte migration and increased activity.
  • Reduction of binucleate cells in the trophectoderm.
  • Weakening of the acellular protein layer between cotyledonary and caruncular epithelium.

Contractions

  • Open endometrial crypts
  • Foetal villi have shrunk due to the escape of blood from the foetal side of the placenta when the umbillical cord ruptures.
  • Myometrial contractions aid exsanguination of the placenta.
  • Separation of foetal membranes.
  • Apex of the allantochorionic sac becomes inverted.
  • As the sac is 'rolled' down the uterine horns, foetal villi are drawn out of the crypts.
  • When a large portion becomes detached and inverted, it forms a mass in the maternal pelvis.
    • Stimulates reflex contractions of abdominal muscles.
    • Completes expulsion of the allantochorionic sac.
  • In polytocious species, dehisence and expulsion of foetal membranes are interspersed with births of the young.
    • Only expulsion of the last afterbirth stimulates abdominal contractions.
  • The final stage of allantochorionic expulsion lasts 1 hour (mare) - 6 hours (cow).
  • Domestic animals normally eat the afterbirth.
    • Not the mare or camelids.

Parturition Behaviour

Mare

Stage 1

Stage 2

Stage 3

Cow

Stage 1

Stage 2

Stage 3

Ewe

Sow

Stage 1

Stage 2

Stage 3

Bitch

Stage 1

Stage 2

Stage 3

Cat

Stage 1

Stage 2

Stage 3

BACK TO REPRODUCTIVE SYSTEM
BACK TO PARTURITION
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