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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| + | <big><center>[[Reproductive_System#Parturition|'''BACK TO PARTURITION''']]</center></big> | ||
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{| style="width:75%; height:200px" border="1" | {| style="width:75%; height:200px" border="1" | ||
| Line 25: | Line 22: | ||
| '''Stage 2: Foetal Expulsion''' | | '''Stage 2: Foetal Expulsion''' | ||
| 12-30 minutes | | 12-30 minutes | ||
| − | | 30 minutes | + | | 30-60 minutes |
| 30-120 minutes | | 30-120 minutes | ||
| 150-180 minutes | | 150-180 minutes | ||
| Line 39: | Line 36: | ||
|} | |} | ||
| + | * 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: | ||
| + | ** [[Parturition - Cervical Softening - Anatomy & Physiology|Cervical Softening]] | ||
| + | ** [[Parturition - Coordinated Myometrial Contraction - Anatomy & Physiology|Coordinated Myometrial Contraction]] | ||
| + | ** Voluntary contraction of abdominal muscles | ||
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| + | |||
| + | == 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 == | + | === Placental Changes === |
During the last 5 days of gestation, there are changes in the placenta. | During the last 5 days of gestation, there are changes in the placenta. | ||
| Line 54: | Line 63: | ||
* Weakening of the acellular protein layer between cotyledonary and caruncular epithelium. | * Weakening of the acellular protein layer between cotyledonary and caruncular epithelium. | ||
| − | == Contractions == | + | === Contractions === |
* 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. |
* Separation of foetal membranes. | * Separation of foetal membranes. | ||
* Apex of the allantochorionic sac becomes inverted. | * Apex of the allantochorionic sac becomes inverted. | ||
| Line 70: | Line 79: | ||
* Domestic animals normally eat the afterbirth. | * Domestic animals normally eat the afterbirth. | ||
** Not the mare or camelids. | ** Not the mare or camelids. | ||
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Revision as of 09:51, 4 August 2008
| 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 |
- The Process by which the conceptus (foetus, placenta and placental membranes) are expelled from the Uterus requires:
- Cervical Softening
- Coordinated Myometrial Contraction
- Voluntary contraction of abdominal muscles
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.