2011 Lab 4

From Embryology

Cardiovascular and Placenta

Section through the placenta

Introduction

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. In this lab, we will also examine placentation.

Objectives

  1. Understand development of early embryo heart and vascular system.
  2. Understand the early placentation events and the development of placental blood vessels.
  3. Brief understanding of prenatal diagnosis and cord stem cells.

Early circulation

Three components of early circulation

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.

The early circulation has 3 components: Vitelline, Embryonic, Placental Each of these has its own system of arteries and veins.

  • 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.
  • 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.
  • 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.

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. (This will be covered in detail in a later Lab)

Three components of early circulation

Stage13 bloodflow.jpg


Cardiovascular Movies

Heart1 looping icon.jpg
Heart Looping

Stage 13 Embryo

Stage 13 3D CVS Reconstruction

Stage13-CVS-icon.jpg

Cardiovascular


About Stage 13 Embryo Sections - This image is from a serial section of a 6mm CRL pig embryo with some features of the Stage 14 embryo. This embryo is approximately equal to the day 42 human embryo. Use these serial images to identify internal features and relationships that exist within the embryo at this stage. Then compare these images with the later features of the Carnegie stage 22 human embryo.

Links: Carnegie stage 13 - serial sections | Carnegie stage 13 | Embryo Serial Sections
Stage 13 image 099-icon.jpg
Stage 13 Serial unlabeled images

A1   A2   A3   A4   A5   A6   A7

B1   B2   B3   B4   B5   B6   B7

C1   C2   C3   C4   C5   C6   C7

D1   D2   D3   D4   D5   D6   D7

E1   E2   E3   E4   E5   E6   E7

F1   F2   F3   F4   F5   F6   F7

G1   G2   G3   G4   G5   G6   G7

Embryo Stage 13 Serial labeled images

A1L  A2L  A3L  A4L  A5L  A6L  A7L

B1L  B2L  B3L  B4L  B5L  B6L  B7L

C1L  C2L  C3L  C4L  C5L  C6L  C7L

D1L  D2L  D3L  D4L  D5L  D6L  D7L

E1L  E2L  E3L  E4L  E5L  E6L  E7L

F1L  F2L  F3L  F4L  F5L  F6L  F7L

G1L  G2L  G3L  G4L  G5L  G6L  G7L

Compare this mid-embryonic cardiovascular system with that existing at the end of embryonic development.

Stage 22 3D CVS Reconstruction

Stage22-CVS-icon.jpg

Cardiovascular

Placentation

Changes in the uterine vasculature with pregnancy
Placenta Links: placenta | Lecture - Placenta | Lecture Movie | Practical - Placenta | implantation | placental villi | trophoblast | maternal decidua | uterus | endocrine placenta | placental cord | placental membranes | placenta abnormalities | ectopic pregnancy | Stage 13 | Stage 22 | placenta histology | placenta vascular | blood vessel | cord stem cells | 2013 Meeting Presentation | Placenta Terms | Category:Placenta
Historic Embryology - Placenta 
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

Compare the features of a normal and gravid uterus.

Chorionic Villi

  • Compare the features of primary, secondary, tertiary and stemmed villi


Human Villi Timeline

The placental vill development data below is based upon a recent immunochemistry confocal laser scanning microscope (CLSM) study.[1] 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.

Fertilization Age

(weeks)

Gestational Age

(weeks)

Vessel Lumen Diameter

(range in microns)

Features
3 to 4 5 and 6 10 - 15
  • a complex network of cords and vessels with redundant connections
  • network comprises mainly cords, already connected together
  • vessels and cords are connected to each other without any interruptions
  • chorionic villus dominated by this network of vascular elements
  • vessels and cords are located centrally as well as peripherally and as a consequence contact the overlying trophoblastic layer
5 to 6 7 and 8 10 - 26
  • villi dominated by capillary network of vessels and cords
  • capillary network contains more vessels than cords
  • chorionic villus tip - regular small branched off (mesenchymal) chorionic villi are present containing CD31 positive cells
7 to 8 9 and 10 60 - 75 two central vessels

26 - 34 capillary network

  • villi have two large centrally located vessels
  • surrounded by and connected to a peripheral capillary network
  • capillary network contains vessels with a lumen in tight contact with overlying trophoblastic layer
  • villous projections also contain blind ending capillary sprouts
9 to 10 11 and 12 70 - 90 two central vessels

26 - 34 capillary network

  • immature intermediate villi characterized by two large vessels surrounded by a capillary network
  • capillary network has few cords
  • blind ending capillary sprouts off the capillary network


CD31 - (PECAM-1, Platelet Endothelial Cell Adhesion Molecule) is a cluster of differentiation molecule found on endothelial and other blood cells.

Histology

Virtual Slides: Placenta and Cord Histology | Virtual Slidebox of Histology

Chorionic villi sampling

Cvs.jpg
  • Chorionic Villus Sampling test is done in the 10th to 12th week after the first day of the mother's last menstrual period (LMP).
  • The test is done by looking at cells taken from the chorionic membrane or placenta.
  • No anaesthetic is required, and a test result is usually available in two to three weeks.
  • When the test is carried out by an obstetrician experienced in the technique, the risk of miscarriage related to the test is about 2 %.

Modified from: Checking your baby's health before birth. State Health Publication Number (PA) 94-090

Ultrasound

Ultrasound12wk 3D image2.jpg Ultrasound12wk 3D image2.jpg 19weeklabel1.jpg Ectopic 01.jpg
12 Week Fetus 12 Week Heart Rate 19 Week Fetus Ectopic Pregnancy

References

  1. <pubmed>17545656</pubmed>

External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.

Course Content 2011

2011 Timetable: | Embryology Introduction | Fertilization | Cell Division/Fertilization | Week 1 and 2 Development | Week 3 Development | Week 1 to 3 | Mesoderm Development | Ectoderm, Early Neural, Neural Crest | Trilaminar Embryo to Early Embryo | Early Vascular Development | Placenta | Vascular and Placenta | Endoderm, Early Gastrointestinal | Respiratory Development | Endoderm and Respiratory | Head Development | Neural Crest Development | Head and Neural Crest | Musculoskeletal Development | Limb Development | Musculoskeletal | Renal Development | Genital | Kidney and Genital | Sensory | Stem Cells | Stem Cells | Endocrine Development | Endocrine | Heart | Integumentary Development | Heart and Integumentary | Fetal | Birth and Revision | Fetal

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. (2019, July 16) Embryology 2011 Lab 4. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2011_Lab_4

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G