Placenta
Umbilical cord
Normal

Author: Paul J. Kowalski, M.D. (see Authors page)

Revised: 17 October 2017, last major update September 2016

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Umbilical cord[title] placenta[title]

Cite this page: Kowalski, P.J. Umbilical cord - normal. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/placentaumbilnormal.html. Accessed December 14th, 2017.
Definition / general
  • Umbilical cord is the anatomic tubular structure that physically connects the developing intrauterine fetus to the placenta, which is anchored to the maternal uterine wall
Essential features
  • Functions as the conduit by which oxygenated, nutrient rich blood from the mother (via the intervening placenta) reaches the fetus
  • Returns deoxygenated, nutrient poor blood from the fetus back to the mother
Terminology
  • Umbilicus (or navel) is the attachment site of the umbilical cord to the fetus
  • Two umbilical arteries in the umbilical cord return deoxygenated blood to the mother
  • One umbilical vein in the umbilical cord carries oxygenated blood to the fetus
  • Wharton jelly is the mucopolysaccharide rich gelatinous substance that provides turgor regulation to the umbilical cord and in which the two umbilical arteries and single umbilical vein are embedded
Clinical features
  • Derived from the allantois and yolk sac during the fifth week of fetal development
  • Fetoplacental circulation (connection) develops when allantoic vessels establish continuity with the developing villi of the placenta
  • Allantoic duct remnant is seen in about 15% of umbilical cords
  • Omphalomesenteric duct remnant is seen in about 1.5% of umbilical cords
  • Two umbilical veins are initially present but one atrophies during the second month of pregnancy
  • Two umbilical arteries, in the vast majority of deliveries (96%), anastomose with 1.5 cm of the placental insertion site
Clinical images

Images hosted on other servers:

Clamped umbilical
cord still
attached to the
fetal umbilicus

Gross description
  • Average size: 55 - 60 cm length and 2.0 - 2.5 cm diameter in a term gestation
  • Pearly white on gross examination, bordering on semitranslucent on closer inspection (due to the gelatinous nature of Wharton jelly)
  • Usually coiled in a counterclockwise direction, approximately 0.1 - 0.2 coils per centimeter of length
  • Insertion on the placenta is normally centrally located by midgestation but may become more eccentric as gestation proceeds
Microscopic (histologic) description
  • Two umbilical arteries have slightly thicker, double layered muscular walls without an elastic layer
  • Single umbilical vein has a thinner muscular wall containing a subintimal elastic layer
  • Intervening Wharton jelly contains loose ground substance, a fine network of microfibrils and scattered nucleated cells (predominantly macrophages, myofibroblasts and mast cells)
  • Umbilical cord is surfaced by a single layer of amnion, which is continuous with the surface of the placenta and the fetal skin
Microscopic (histologic) images

Images hosted on other servers:

Normal three vessel umbilical cord