Placenta - Cord

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Introduction

left)
Histology Human placental cord cross-section
Human placental cord cross-section

The placenta (Greek, plakuos = flat cake) named on the basis of this organs appearance. The placental cord (umbilical cord) is the connecting region between the functional placenta and the embryo/fetal umbilical region. The human cord varies greatly in overall length increasing to about 60 to 70 cm at term. This extraembryonic structure contains the placental blood vessels and allantois.


There are essentially 3 separate aortic/venous circulatory systems: umbilical, systemic and vitelline. The umbilical system is lost at birth, the vitelline contributes to the portal system and the systemic (embryonic) is extensively remodelled to fom the the cardiovascular system.


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 first trimester placenta | 1960 monkey | 1972 Placental circulation | Historic Disclaimer

Some Recent Findings

Model of the Human Embryo
Human Embryo Cord Model (stage 17
  • Human Chorionic Gonadotropin Induces Human Macrophages to Form Intracytoplasmic Vacuoles Mimicking Hofbauer Cells in Human Chorionic Villi[1] The most characteristic morphological feature of macrophages in the stroma of placental villi, known as Hofbauer cells, is their highly vacuolated appearance. They also show positive immunostaining for human chorionic gonadotropin (hCG)."
  • Hofbauer cells in early human placenta: possible implications in vasculogenesis and angiogenesis[2] "The stroma of the placental villi contain numerous macrophages, so-called Hofbauer cells which are of mesenchymal origin and are thought to function in many processes. ...Double immunohistochemistry staining with CD31/PECAM1 and CD68 was applied to placental tissues. In placental villous core, majority of the Hofbauer cells were found to be either in close contact with angiogenic cell cords and primitive vascular tubes or located in between them. Moreover, the number of Hofbauer cells and vasculogenic structures were found to be significantly correlated. The findings of this study suggest for the first time that Hofbauer cells might be involved in the processes of vasculogenesis and angiogenesis in the placenta."
More recent papers
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Search term: Placental Cord

<pubmed limit=5>Placental Cord</pubmed>

Hofbauer Cells

Hofbauer Cells

Hofbauer Cells (red asterisks)[3]

  • human villous macrophages
  • highly vacuolated cells
  • located the core of placental villi
  • macrophages with micropinocytotic activity and phagocytosis ability
  • possible paracrine role for early stages of placental vasculogenesis
  • express angiogenic growth factors (VEGF)
Historic Embryology - Hofbauer Cells
Chapter 14. Hofbauer Cells in Normal and Pathologic Conceptuses Contributions to Embryology Carnegie Institution No.56 (1921)
Historic Disclaimer - information about historic embryology pages 
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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Wharton's Jelly

Placental cord 01.jpg

Placental cord cross-section showing Wharton's Jelly

First described and named after Thomas Wharton (1614–1673) an English physician and anatomist.
  • placental cord connective tissue (substantia gelatinea funiculi umbilicalis)
  • amorphous substance containing glycosaminoglycans, proteoglycans and hyaluronic acid.
  • cells similar to smooth muscle that allows a contractile function.
  • network of collagen that form canaliculi and perivascular spaces.
  • maintain blood flow to the fetus during placental cord compression during pregnancy or delivery.

Placental Cord Histology

Hubrecht Homo73a cord 1.jpg

Human placental cord (3.5 month) cross-section.


Persistent Right Umbilical Vein

A fairly rare anomaly, a study of 15,237 obstetric ultrasound examinations performed after 15 weeks' gestation identified only 33 cases of persistent right umbilical vein.[4] Some studies have identified associated fetal anomalies with this condition[5], including cardiac abnormalities.[6]


Cord Length

The following are lengths and classifications at term.

  • Normal range - 50 to 60 cm.
  • Short cord - less than 35 cm.
  • Long cords - over 70 cm can be associated with wrapping around the fetus and other abnormalities.[7]

Cord Coiling

A recent review of the published literature on cord coiling[8] states: "Previous studies that draw a link between abnormal cord coiling and clinical outcome are generally too small and/or selective to allow meaningful conclusions or applicability to low-risk populations."

The following suggested associations[9] should therefore be reconsidered.

  • Hypocoiling - associated with increased incidence of fetal demise, intrapartum fetal heart rate decelerations, operative delivery for fetal distress, anatomic-karyotypic abnormalities and chorio-amnionitis.
  • Hypercoiling - associated with increased incidence of fetal growth restriction, intrapartum fetal heart rate decelerations, vascular thrombosis and cord stenosis.

Placental Cord Ultrasound

Placental cord ultrasound 03.jpg

There are a number of analyses that can be made by ultrasound scanning of the fetal placental cord. Some detected abnormalities (blood vessel number, blood flow[10]) have been associated with adverse developmental outcomes.

  • Quantification of cord length, diameter, structural abnormalities.
  • Quantification of placental blood vessel number and size.
  • Quantification of uterine artery blood flow (doppler analysis).

Ultrasound image of transverse scan through the cord show the method of estimation of the cross-sectional area.


Placental cord ultrasound 04.jpg

Cord Abnormalities

Cord Vessel Number

Cord with one artery and one vein

Persistent Right Umbilical Vein

A fairly rare anomaly, a study of 15,237 obstetric ultrasound examinations performed after 15 weeks' gestation identified only 33 cases of persistent right umbilical vein.[11] Some studies have identified associated fetal anomalies with this condition[12], including cardiac abnormalities.[13]

Cord Knotting

Placental cord true knot

There are few abnormalities associated with umbilical cord development, other that abnormally short or long cords, which in most cases do not cause difficulties.

In some cases though, long cords can wrap around limbs or the fetus neck, which can then restrict blood flow or lead to tissue or nerve damage, and therefore effect develoment.

Cord knotting can also occur (1%) in most cases these knots have no effect, in some cases of severe knotting this can prevents the passage of placental blood.

Umbilical Cord Torsion

Rare umbilical cord torsion, even without knot formation can also affect placental blood flow, even leading to fetal demise.[14]

Cord Length

References

  1. <pubmed>23128164</pubmed>
  2. <pubmed>17350092</pubmed>
  3. <pubmed>22606231</pubmed>| PLoS One.
  4. <pubmed>7970470</pubmed>
  5. <pubmed>20922781</pubmed>
  6. <pubmed>26635256</pubmed>
  7. <pubmed>11178630</pubmed>
  8. <pubmed>24259031</pubmed>
  9. <pubmed>16076615</pubmed>
  10. <pubmed>24277892</pubmed>
  11. <pubmed>7970470</pubmed>
  12. <pubmed>20922781</pubmed>
  13. <pubmed>26635256</pubmed>
  14. <pubmed>7966052 </pubmed>

Reviews

Articles

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May 2010 search "Placental Cord Development]" All (650) Review (91) Free Full Text (119)


Search Pubmed: Placental Cord | Umbilical Cord | Placental Cord Development | Umbilical Cord Development | Hofbauer cells


Additional Images

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Cite this page: Hill, M.A. (2024, March 30) Embryology Placenta - Cord. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Placenta_-_Cord

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