Difference between revisions of "Normal Parturition - Anatomy & Physiology"
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− | + | ==Stages of Parturition== | |
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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. | ||
+ | *Stage 2: the expulsive stage, characterised by the onset of abdominal contractions which together with uterine contractions lead to foetal expulsion | ||
+ | *Stage 3: separation and expulsion of the foetal membranes. In polycotous species second and third stages are often inter-mixed. | ||
+ | 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 | ||
− | | 30- | + | | 30 minutes - 4 hours |
| 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 | |
− | Parturition is the | + | to occur |
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== 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. | ||
− | * Myometrial contractions aid exsanguination of the placenta. | + | * [[Uterine Contraction - Anatomy & Physiology|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. | ||
− | = | + | == 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. | ||
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− | == | + | == Parturition Behaviour == |
− | == | + | === [[Parturition Behaviour - Mare|Mare]] === |
− | === | + | ===[[Parturition Behaviour - Cow| Cow]] === |
− | === | + | ===[[Parturition Behaviour - Ewe| Ewe]] === |
− | === | + | ===[[Parturition Behaviour - Sow| Sow]] === |
− | == | + | ===[[Parturition Behaviour - Bitch| Bitch]] === |
− | == | + | ===[[Parturition Behaviour - Cat| Cat]] === |
− | |||
− | + | {{OpenPages}} | |
+ | [[Category:Parturition]] | ||
+ | [[Category:Bullet Points]] |
Latest revision as of 18:27, 3 July 2012
Stages of Parturition
- 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.
- Stage 2: the expulsive stage, characterised by the onset of abdominal contractions which together with uterine contractions lead to foetal expulsion
- Stage 3: separation and expulsion of the foetal membranes. In polycotous species second and third stages are often inter-mixed.
The following table summarises the normal time taken to progress through the stages of parturition in different species.
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 minutes - 4 hours | 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 |
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; this requires cervical softening,coordinated myometrial contractions and contraction of abdominal muscles to occur
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.
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.
Parturition Behaviour
Mare
Cow
Ewe
Sow
Bitch
Cat
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