ASA Meeting 2013 - Placenta

Placenta Embryology and Circulation

Australian Sonographers Association (ASA) Annual Conference 2013 Educate Innovate Celebrate May 17 to 19 May 2013

Links: Conference Homepage | Sonographers Association | Placenta Development | Embryology

Draft Page - notice removed when complete.

Introduction

This page will be updated and contain the final conference presentation.

Abstract

Dr Mark Hill

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).

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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). green cells - trophoblast layer of the conceptus blue cells - epiblast layer of the bilaminar embryo yellow cells - hypoblast layer of the bilaminar embryo white cells - uterine endometrium epithelium red - maternal blood vessel Implantation Movie Links: MP4 version | Week 2 Chorionic Cavity Movie | Implantation | Week 2 | Trophoblast | Human Chorionic Gonadotropin | Placenta Development | Movies

<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. white cells - (left) endometrial gland (right) endometrial epithelium blue - epiblast layer (forming ectoderm and amniotic cavity lining) yellow - hypoblast layer (replaced with endoderm during gastrulation) red cells - extraembryonic mesoderm layer green - trophoblast layers (cytotrophoblast and syncitiotrophoblast) red spaces - blood-filled spaces, maternal lacunae Links: MP4 version | Quicktime version | Implantation Movie | Week 2 | Movies

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

Placenta Vasculature - MRI and CT

Term placenta viewed from the fetal side.

Magnetic Resonance Angiography (MRA)	Computed Tomography Angiography (CTA)
Legend CA - chorionic artery PSA - primary stem artery SSA - secondary stem artery TSA - tertiary stem artery

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

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Cite this page: Hill, M.A. (2024, April 18) Embryology ASA Meeting 2013 - Placenta. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/ASA_Meeting_2013_-_Placenta

What Links Here?

© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G