ASA Meeting 2013 - Placenta: Difference between revisions
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[[File:Placental volume graph.jpg|thumb|300px|Term Placenta Measurements]] | [[File:Placental volume graph.jpg|thumb|300px|Term Placenta Measurements]] | ||
Morphometric indices at term of placental composition, villous capillarization and the mean cross-sectional areas of peripheral villi and capillaries. | Morphometric indices at term of placental composition, villous capillarization and the mean cross-sectional areas of peripheral villi and capillaries. | ||
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Data from a study sample of 15 normal placenta, mean placental volume, 652 ml.<ref name=PMID18328557><pubmed>18328557</pubmed></ref><ref><pubmed>19141109</pubmed></ref> | |||
* Microscopical fields on stained sections were selected by systematic uniform random sampling and analysed stereologically to estimate the volumes of placental compartments and total lengths of villi and fetal capillaries. | * Microscopical fields on stained sections were selected by systematic uniform random sampling and analysed stereologically to estimate the volumes of placental compartments and total lengths of villi and fetal capillaries. | ||
* Mean cross-sectional areas of peripheral villi and capillaries, together with measures of villous capillarization (capillary volume densities and capillary : villus length ratios), were derived from global volumes and lengths. | * Mean cross-sectional areas of peripheral villi and capillaries, together with measures of villous capillarization (capillary volume densities and capillary : villus length ratios), were derived from global volumes and lengths. |
Revision as of 11:46, 12 May 2013
Placenta Embryology and Circulation
Australian Sonographers Association (ASA) Annual Conference 2013
Educate Innovate Celebrate
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Draft Page - notice removed when complete.
Introduction
This page will be updated and contain the final conference presentation.
Abstract
Sonographic analysis of the placenta and uterus and their associated blood flow are key diagnostic prenatal assessments in human development. This review will provide an overview of the basic biology of the placentation process and key events in the developmental timeline. This talk should be of value to those wanting a better understanding of the process of human haemochorial placentation.
Placentation begins at the implantation site in the second week of development (GA week 4) with conceptus trophoblast cells invading the maternal endometrial epithelium and stroma. From that time on the process of placentation involves complex interactions between maternal uterine and fetal tissues. While there are many animal models of this process, none currently exactly match that seen in humans.
Maternally, these changes include modification of the maternal vascular, endocrine and immune response. Fetally, an entire organ is grown from extra-embryonic tissue that has many functions outside of acting as a simple exchange tissue. The main maternal vascular changes include increased vascularity and trophoblast modification of spiral arteries. The fetal vascular bed consists of large cord vessels and an exponentially growing capillary bed consisting of kilometres of villous capillaries. Identification of cord vessel number, size and blood flow, are important indices of normal fetal development. Furthermore extensive remodeled of the capillary bed occurs throughout development, with some villi morphologies influencing the efficiency of diffusional gas exchange. Clinically, abnormalities of placentation site, placental development, function and blood flow can have both maternal and fetal ramifications.
The full presentation and additional information/resources/links is available online (http://embryology.med.unsw.edu.au/embryology/index.php?title=ASA_Meeting_2013_-_Placenta).
Historic drawing of Fetus and Placenta
Table 7 De formato foetu liber singularis (1626) by Adriaan van den Spiegel (1578-1625)
Embryo GA Week 4 (Week 2)
<mediaplayer width='250' height='260' image="http://embryology.med.unsw.edu.au/embryology/images/a/a9/Week2_001_icon.jpg">File:Week2_001.mp4</mediaplayer> |
This animation shows the process of implantation, occurring during week 2 of development in humans. The beginning of the animation shows adplantation to the the uterus lining (endometrium epithelium). The hatched blastocyst with a flat outer layer of trophoblast cells (green), the inner cell mass which has formed into the bilaminar embryo (epiblast and hypoblast) and the large fluid-filled space (blastocoel).
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<mediaplayer width='220' height='260' image="http://embryology.med.unsw.edu.au/embryology/images/0/08/Chorion_001_icon.jpg">File:Chorion 001.mp4</mediaplayer> | Animation shows the events following implantation and focuses on changes in the the spaces surrounding the embryonic disc, the extraembryonic coelom.
The blastoceol cavity is converted into two separate spaces: the yolk sac and the chorionic cavity. The third space lies above the epiblast layer of the embryonic disc, the amniotic cavity.
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Embryo GA Week 7 (Week 5)
- Embryo Links: Embryo and Placenta | Embryo | Embryo (label) | Embryo (animated) | Embryo (animated large) | Head region | Head region (label) | Body region | Body region (label) | Carnegie stage 13
Embryo GA Week 9 (Week 7)
Embryo in gestational sac | Embryo open sac |
Embryo with placentation (ectopic) | Embryo in amniotic sac |
Villi Development
Secondary Villi | Tertiary Villi |
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Term Placenta
Placenta Vasculature - MRI and CT
Term placenta viewed from the fetal side.[1]
Magnetic Resonance Angiography (MRA) | Computed Tomography Angiography (CTA) |
Legend
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Placenta Measurements
Morphometric indices at term of placental composition, villous capillarization and the mean cross-sectional areas of peripheral villi and capillaries.
Variable | Unit | Placenta |
Intervillous space | mL | 213 |
Stem villi | mL | 71.4 |
Peripheral villi | mL | 326 |
Trophoblast | mL | 95.5 |
Stroma | mL | 184 |
Fetal capillaries | mL | 46.9 |
Non-parenchyma | mL | 41.5 |
Peripheral villi | km | 89.2 |
Fetal capillaries | km | 310 |
TS area villi | µm2 | 3700 |
TS area capillary | µm2 | 150 |
Capillaries | mL mL-1 | 0.147 |
Length ratio | km km-1 | 3.6 |
Data from a study sample of 15 normal placenta, mean placental volume, 652 ml.[2][3]
- Microscopical fields on stained sections were selected by systematic uniform random sampling and analysed stereologically to estimate the volumes of placental compartments and total lengths of villi and fetal capillaries.
- Mean cross-sectional areas of peripheral villi and capillaries, together with measures of villous capillarization (capillary volume densities and capillary : villus length ratios), were derived from global volumes and lengths.
Online Placenta Links
Historic Embryology - Placenta |
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1883 Embryonic Membranes | 1907 Development Atlas | 1909 | 1910 Textbook | 1917 Textbook | 1921 Textbook | 1921 Foetal Membranes |1921 human | 1921 Pig implantation | 1922 Single placental artery | 1923 Placenta Review | 1939 umbilical cord | 1943 human and monkey | 1944 chorionic villus and decidua parietalis | 1946 placenta ageing | 1960 monkey | 1972 Placental circulation | Historic Disclaimer |
References
- ↑ <pubmed>20226038</pubmed>| BMC Physiol.
- ↑ <pubmed>18328557</pubmed>
- ↑ <pubmed>19141109</pubmed>
Books
- Wang Y, Zhao S. Vascular Biology of the Placenta. San Rafael (CA): Morgan & Claypool Life Sciences; 2010. Available from: http://www.ncbi.nlm.nih.gov/books/NBK53247
Glossary Links
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2024, April 23) Embryology ASA Meeting 2013 - Placenta. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/ASA_Meeting_2013_-_Placenta
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G