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| =Cardiovascular and Placenta=
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| == Introduction ==
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| This laboratory will explore the development of the embryonic cardiovascular system, which includes the placental vascular system. We will look through cross-sections of the Carnegie stage 13 embryo and follow the flow of blood through the embryonic vasculature.
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| In this lab, we will also examine placentation.
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| ==Objectives==
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| # Understand development of early embryo heart and vascular system.
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| # Understand the early placentation events and the development of placental blood vessels.
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| == Early circulation ==
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| [[Image:Embryonic Circulations.jpg|thumb|right|Three components of early circulation]]
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| The vascular system of the embryo is formed from blood islands that appear in the extraembryonic mesoderm of the yolk sac and the embryonic mesoderm (primarily splanchnic mesoderm). Both of these clusters fuse together and extend, forming a vast network.
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| The early circulation has 3 components: Vitelline, Embryonic, Placental Each of these has its own system of arteries and veins.
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| * '''Vitelline''' - (not shown) the vitelline arteries branch off the dorsal aortas and enter the yolk sac, covering its entire surface. The vitelline veins return red blood cells from the capillary beds to the sinus venosus, posterior to the heart. The vitelline vessels eventually contribute to the portal system of the liver in the adult.
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| * '''Embryonic''' - blood from the dorsal aorta enters intersegmental arteries, including the arteries of the pharyngeal arches. The blood returns to the heart via the anterior and posterior cardinal veins.
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| * '''Placental''' - the umbilical arteries receive blood from the aorta. This is carried to the chorionic villi, where exchange occurs with the mother. Waste products are disposed of, nutrients and oxygen are collected, and then the umbilical veins convey the blood to the sinus venosus.
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| '''Heart''' - The heart develops from cardiogenic mesoderm, a region of splanchnic mesoderm lying above the buccopharyngeal membrane. Development begins in week 3 with the formation of a pair of heart tubes. These fuse and form a single tube in week 4, as a result of the embryonic folding processes that occur. As the heart grows, septation events occur, transforming it into a 4-chambered pump. Initially, the ventricles develop above the atria; however simultaneous growth and bending of the tube bring the structures into correct position. In humans, the heart begins to beat on day 22-23.
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| [[Image:Heart Tube Segments.jpg|thumb|right|Three components of early circulation]]
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| [[File:Stage13_bloodflow.jpg]]
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| ====Cardiovascular Movies====
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| {| border='0px'
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| | [[File:Heart1_looping icon.jpg|90px|link=Development_Animation_-_Heart Looping]]
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| | [[Development_Animation_-_Heart Looping|Heart Looping]]
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| == Stage 13 Embryo ==
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| '''Stage 13 3D CVS Reconstruction'''
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| [[File:Stage13-CVS-icon.jpg|150px|link=Movie_-_Cardiovascular_3D_stage_13]]
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| [[Movie_-_Cardiovascular_3D_stage_13|Cardiovascular]]
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| {{Template:Stage13sections}}
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| Compare this mid-embryonic cardiovascular system with that existing at the end of embryonic development.
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| '''Stage 22 3D CVS Reconstruction'''
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| [[File:Stage22-CVS-icon.jpg|150px|link=Movie_-_Cardiovascular_3D_stage_22]]
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| [[Movie_-_Cardiovascular_3D_stage_22|Cardiovascular]]
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| == Placentation ==
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| {{Placenta Links}}
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| Compare the features of a normal and gravid uterus.
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| '''Virtual Slides:''' [http://vslides.unsw.edu.au/VirtualSlideV2.nsf/id/E8BDC2 Placenta and Cord Histology]
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| [[Image:Uterine and placental vasculature.jpg|thumb|right|Changes in the uterine vasculature with pregnancy]]
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| [[Image:Cvs.jpg|thumb|right|Chorionic villi sampling]]
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| ==Chorionic Villi==
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| * Compare the features of primary, secondary, tertiary and stemmed villi
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| <gallery>
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| File:Gray0036.gif|Primary chorionic villi
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| File:Gray0037.gif|Secondary chorionic villi
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| File:Placenta anchoring villi.jpg|Placenta anchoring villi
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| </gallery>
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| ==Human Villi Timeline==
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| The placental vill development data below is based upon a recent immunochemistry confocal laser scanning microscope (CLSM) study.<ref><pubmed>17545656</pubmed></ref>
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| Note that the paper uses clinical gestational age (GA) from last menstrual period (LMP) and has been corrected for post-conception (fertilization) age, approximately 14 days later.
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| {|
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| |-bgcolor="CEDFF2"
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| | width= 100px|'''Fertilization Age'''
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| (weeks)
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| | width= 100px|'''Gestational Age'''
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| (weeks)
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| | width= 120px|'''Vessel Lumen Diameter'''
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| (range in microns)
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| | width= 300px valign=top|'''Features'''
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| | 3 to 4
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| | 5 and 6
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| | 10 - 15
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| * a complex network of cords and vessels with redundant connections
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| * network comprises mainly cords, already connected together
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| * vessels and cords are connected to each other without any interruptions
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| * chorionic villus dominated by this network of vascular elements
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| * vessels and cords are located centrally as well as peripherally and as a consequence contact the overlying trophoblastic layer
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| |-bgcolor="F5FAFF"
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| | 5 to 6
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| | 7 and 8
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| | 10 - 26
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| * villi dominated by capillary network of vessels and cords
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| * capillary network contains more vessels than cords
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| * chorionic villus tip - regular small branched off (mesenchymal) chorionic villi are present containing CD31 positive cells
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| | 7 to 8
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| | 9 and 10
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| | 60 - 75 two central vessels
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| 26 - 34 capillary network
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| * villi have two large centrally located vessels
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| * surrounded by and connected to a peripheral capillary network
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| * capillary network contains vessels with a lumen in tight contact with overlying trophoblastic layer
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| * villous projections also contain blind ending capillary sprouts
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| |-bgcolor="F5FAFF"
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| | 9 to 10
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| | 11 and 12
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| | 70 - 90 two central vessels
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| 26 - 34 capillary network
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| * immature intermediate villi characterized by two large vessels surrounded by a capillary network
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| * capillary network has few cords
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| * blind ending capillary sprouts off the capillary network
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| |}
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| '''CD31''' - (PECAM-1, Platelet Endothelial Cell Adhesion Molecule) is a cluster of differentiation molecule found on endothelial and other blood cells.
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| [[Image:Gray0039.gif|thumb|Section through the placenta]]
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| ==References==
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| <references/>
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| ==External Links==
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| '''Embryo Images Unit:''' [http://www.med.unc.edu/embryo_images/ Embryo Images Online] Early Cell Populations (cardiogenic section) | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardevtoc.htm Cardiovascular Development] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev001.htm Week 3 Development] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev007.htmhttp://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev007.htm Week 4 Development] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev018.htm Heart Chambers and Outflow Tract] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev022.htm Atrioventricular Septation] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev028.htm Outflow Tract Septation] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev035.htm Ventricular Septation] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev036.htm Atrial Septation] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev040.htm Atrial Walls] [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev041.htm Aortic Arch Vessels] | [http://www.med.unc.edu/embryo_images/unit-cardev/cardev_htms/cardev042.htm Changes at Birth]
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| [http://share.eldoc.ub.rug.nl/FILES/root2/2010/Mesestcei/Castrechini_2010_Placenta.pdf Mesenchymal stem cells in chorionic villi]
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| [[Category:2011ANAT2341]]
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| [[Category:Science-Undergraduate]]
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| [[Category:Heart]]
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| [[Category:Cardiovascular]]
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