Placenta - Cord

Introduction

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. This extraembryonic structure contains the placental blood vessels.

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.

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

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Some Recent Findings

Hofbauer cells in early human placenta: possible implications in vasculogenesis and angiogenesis^[1] "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."

Hofbauer cells

Placental Cord Histology

Placental cord cross-section
Placental vein
Placental artery
Placental allantois

Placental Cord Ultrasound

Placental cord ultrasound measurements

Cord Abnormalities

Cord Vessel Number

Cord with one artery and one vein

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.

See WebPath images: umbilical cord knot 1 | umbilical cord knot 2 | Pseudoknot of umbilical cord, gross

References

Umbilical cord torsion

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

Hallak M, Pryde PG, Qureshi F, Johnson MP, Jacques SM, Evans MI. Constriction of the umbilical cord leading to fetal death. A report of three cases. J Reprod Med. 1994 Jul;39(7):561-5. Review.

See WebPath images: Torsion of umbilical cord, gross | Torsion of umbilical cord, with fetal demise, gross