2010 BGD Practical 12 - Third Trimester: Difference between revisions
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==Introduction== | ==Introduction== | ||
[[File:Frazer006_bw600.jpg|thumb|300px|Historic drawing of the fetus in the uterus at 8 months compared to non-pregnant uterus size.]] | |||
* Fetal Neural | * Fetal Neural | ||
* Fetal Respiratory | * Fetal Respiratory | ||
* Fetal Cardiovascular | * Fetal Cardiovascular | ||
* survival issues for early delivery | |||
* fetal weight | * fetal weight | ||
* fetal origins hypothesis | * fetal origins hypothesis | ||
===Practical Audio=== | |||
{| border='0px' | |||
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| [[File:Mark_Hill.jpg|60px|left]] | |||
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BGD Cycle A 2010 Audio - Dr Mark Hill Monday 17th May 2010 3-5pm G2G4. | |||
:Note - this is a live unedited recording from the practical and may contain errors in either descriptions or content. | |||
[[Media:Lab 12-05.mp3|listen Part 5]] | [[:File:Lab 12-05.mp3|download]] (820 Kb MP3 6:59) | |||
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==Week 24+== | |||
* Earliest potential survival expected if born | |||
* Respiratory Week 24 to 40 lung histology - terminal sac, end month 6 alveolar cells type 2 appear and begin to secrete surfactant | |||
** saccule - a large thin-walled airspace lined by flattened epithelium present from about 28 weeks gestation to 2 months after birth | |||
* Gonad - male gonad (testes) descending (week 30) [[Development Animation - Testis Descent]] | |||
** 10 to 23 weeks - (9.45%) had migrated from the abdomen and were situated in the inguinal canal | |||
** 24 to 26 weeks - (57.9%) had migrated from the abdomen | |||
** 27 to 29 weeks - (16.7%) had not descended to the scrotum | |||
{| border='0px' | |||
| [[File:Testis_001 icon.jpg|120px|link=Development_Animation_-_Testis_Descent]] | |||
| [[Development_Animation_-_Testis_Descent|Testis Descent]] Failure of descent ([[C#cryptorchidism|cryptorchidism]]) either unilateral or bilateral testicular descent, occurring in up to 30% premature and 3-4% term males. | |||
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References: Sampaio FJ, Favorito LA. Analysis of testicular migration during the fetal period in humans. J Urol. 1998 Feb;159(2):540-2. | Malas MA, Sulak O, Ozturk A. The growth of the testes during the fetal period. BJU Int. 1999 Oct;84(6):689-92. | |||
==Fetal Weight== | |||
[[File:Fetal weight change.jpg|600px]] | |||
==Fetal Birth== | |||
Most of the serious illness and mortality is concentrated in the 1 to 2 percent of infants who are born at less than 32 weeks of gestation (week 30) and who weigh less than 1500 g. | |||
==Teratogens - Infant Drug Clearance== | |||
[[Image:Drug-clearance-rates.png|thumb|Drug clearance rates]] | |||
'''Teratogen''' (Greek, ''teraton'' = monster) Any agent that causes a structural abnormality following exposure during pregnancy. The overall effect depends on dosage and time of exposure. | |||
The drug clearance data below are only approximate calculated rates for the fetus and infant from [http://www.medsafe.govt.nz/Profs/PUarticles/lactation.htm#Infants NZ Drug Safety in Lactation] | |||
{| class="prettytable" | |||
|-bgcolor="lightsteelblue" | |||
| '''Post-conceptual Age''' (weeks) | |||
| '''Clearance of Drug''' (percentage of adults) | |||
|- | |||
| 24-28 | |||
| 5% | |||
|- | |||
| 28-34 | |||
| 10% | |||
|- | |||
| 34-40 | |||
| 33% | |||
|- | |||
| 40-44 | |||
| 50% | |||
|- | |||
| 44-68 | |||
| 66% | |||
|-bgcolor="lightsteelblue" | |||
| > 68 | |||
| 100% | |||
|} | |||
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{{Template:BGDFooter2010}} | {{Template:BGDFooter2010}} | ||
[[Category:Third Trimester]] |
Latest revision as of 09:29, 15 June 2010
Practical 12: Embryo to Fetus | Second Trimester | Third Trimester | Birth | Neonatal | Abnormalities
Introduction
- Fetal Neural
- Fetal Respiratory
- Fetal Cardiovascular
- survival issues for early delivery
- fetal weight
- fetal origins hypothesis
Practical Audio
BGD Cycle A 2010 Audio - Dr Mark Hill Monday 17th May 2010 3-5pm G2G4.
listen Part 5 | download (820 Kb MP3 6:59) |
Week 24+
- Earliest potential survival expected if born
- Respiratory Week 24 to 40 lung histology - terminal sac, end month 6 alveolar cells type 2 appear and begin to secrete surfactant
- saccule - a large thin-walled airspace lined by flattened epithelium present from about 28 weeks gestation to 2 months after birth
- Gonad - male gonad (testes) descending (week 30) Development Animation - Testis Descent
- 10 to 23 weeks - (9.45%) had migrated from the abdomen and were situated in the inguinal canal
- 24 to 26 weeks - (57.9%) had migrated from the abdomen
- 27 to 29 weeks - (16.7%) had not descended to the scrotum
Testis Descent Failure of descent (cryptorchidism) either unilateral or bilateral testicular descent, occurring in up to 30% premature and 3-4% term males. |
References: Sampaio FJ, Favorito LA. Analysis of testicular migration during the fetal period in humans. J Urol. 1998 Feb;159(2):540-2. | Malas MA, Sulak O, Ozturk A. The growth of the testes during the fetal period. BJU Int. 1999 Oct;84(6):689-92.
Fetal Weight
Fetal Birth
Most of the serious illness and mortality is concentrated in the 1 to 2 percent of infants who are born at less than 32 weeks of gestation (week 30) and who weigh less than 1500 g.
Teratogens - Infant Drug Clearance
Teratogen (Greek, teraton = monster) Any agent that causes a structural abnormality following exposure during pregnancy. The overall effect depends on dosage and time of exposure.
The drug clearance data below are only approximate calculated rates for the fetus and infant from NZ Drug Safety in Lactation
Post-conceptual Age (weeks) | Clearance of Drug (percentage of adults) |
24-28 | 5% |
28-34 | 10% |
34-40 | 33% |
40-44 | 50% |
44-68 | 66% |
> 68 | 100% |
Practical 12: Embryo to Fetus | Second Trimester | Third Trimester | Birth | Neonatal | Abnormalities
Additional Information
The following information is a detailed timeline of third trimester development and content does not form part of the current practical class.
Third Trimester
(Clinical Week 28)
Event | ||
Clinical third trimester | Sense - Hearing 3rd Trimester - vibration acoustically of maternal abdominal wall induces startle respone in fetus. | |
Respire Month 7 - respiratory bronchioles proliferate and end in alveolar ducts and sacs | ||
Genital male gonad (testes) descending | ||
Neural brain cortical sulcation - primary sulci present PMID:11158907 | ||
Neural brain cortical sulcation - insular, cingular, and occipital secondary sulci present PMID:11158907 | ||
Birth | Clinical Week 40
Heart pressure difference closes foramen ovale leaving a fossa ovalis Thyroid TSH levels increase, thyroxine (T3) and T4 levels increase to 24 h, then 5-7 days postnatal decline to normal levels Adrenal - zona glomerulosa, zona fasiculata present
|
Glossary Links
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- 2010 BGD: Lecture 1 | Lecture 2 | Practical 3 | Practical 6 | Practical 12
Cite this page: Hill, M.A. (2024, March 29) Embryology 2010 BGD Practical 12 - Third Trimester. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2010_BGD_Practical_12_-_Third_Trimester
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G