The umbilical vein is a

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

present during

fetal development Prenatal development () involves the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal deve ...

that carries

oxygenated blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the Cell (biology), cells, and transports Metabolic waste, metabolic waste products away from th ...

from the

placenta The placenta (: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas, and waste exchange between ...

into the growing

fetus A fetus or foetus (; : fetuses, foetuses, rarely feti or foeti) is the unborn offspring of a viviparous animal that develops from an embryo. Following the embryonic development, embryonic stage, the fetal stage of development takes place. Pren ...

. The umbilical vein provides convenient access to the central circulation of a neonate for restoration of blood volume and for administration of glucose and drugs. The blood pressure inside the umbilical vein is approximately 20

mmHg A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high. Currently, it is defined as exactly , or approximately 1 torr = atmosphere = &nb ...

.Wang, Y. Vascular biology of the placenta. in Colloquium Series on Integrated Systems Physiology: from Molecule to Function. 2010. Morgan & Claypool Life Sciences.

Fetal circulation

The unpaired umbilical vein carries oxygen and nutrient rich blood derived from fetal-maternal blood exchange at the

chorionic villi Chorionic villi are Wiktionary:villus, villi that sprout from the chorion to provide maximal contact area with maternal blood. They are an essential element in pregnancy from a histology, histomorphologic perspective, and are, by definition, a pr ...

. More than two-thirds of fetal hepatic circulation is via the main

portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approxima ...

, while the remainder is shunted from the left portal vein via the ductus venosus to the

inferior vena cava The inferior vena cava is a large vein that carries the deoxygenated blood from the lower and middle body into the right atrium of the heart. It is formed by the joining of the right and the left common iliac veins, usually at the level of the ...

, eventually being delivered to the fetal

right atrium The atrium (; : atria) is one of the two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular mitral and tricuspid heart valves. ...

Closure

Closure of the umbilical vein usually occurs after the

umbilical arteries The umbilical artery is a paired artery (with one for each half of the body) that is found in the abdominal and pelvic regions. In the fetus, it extends into the umbilical cord. Structure Development The umbilical arteries supply systemic arte ...

have closed. This prolongs the communication between the placenta and fetal heart, allowing for a sort of

autotransfusion Autotransfusion is a process wherein a person receives their own blood for a Blood transfusion, transfusion, instead of blood bank, banked allogenic (separate-Blood donor, donor) blood. There are two main kinds of autotransfusion: Blood can be Aut ...

of remaining blood from the placenta to the fetus. Within a week of birth, the neonate's umbilical vein is obliterated and is replaced by a fibrous cord called the round ligament of the liver (also called '). It extends from the umbilicus to the transverse fissure, where it joins with the

falciform ligament of the liver In human anatomy, the falciform ligament () is a ligament that attaches the liver to the front body wall and divides the liver into the left lobe and right lobe. The falciform ligament is a broad and thin fold of peritoneum, its base being dire ...

to separate segment 4 from segments 2 and 3 of the left hepatic lobe.

Recanalization

Under extreme

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

, the round ligament may reopen to allow the passage of blood. Such recanalization may be evident in patients with

cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, chronic liver failure or chronic hepatic failure and end-stage liver disease, is a chronic condition of the liver in which the normal functioning tissue, or parenchyma, is replaced ...

and

portal hypertension Portal hypertension is defined as increased portal venous pressure, with a hepatic venous pressure gradient greater than 5 mmHg. Normal portal pressure is 1–4 mmHg; clinically insignificant portal hypertension is present at portal pressures 5� ...

. Patients with cirrhosis experience rapid growth of scar tissue in and around the liver, often functionally obstructing nearby vessels.

Vessel occlusion Vascular occlusion is a blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cau ...

increases

vascular resistance Vascular resistance is the resistance that must be overcome for blood to flow through the circulatory system. The resistance offered by the systemic circulation is known as the systemic vascular resistance or may sometimes be called by another ter ...

and therefore leads to hypertension. In portal hypertension, the vessels surrounding the

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

are subjected to abnormally high blood pressure—so high, in fact, that the force of the blood pressing against the round ligament is sufficient to recanalize the structure. This leads to a condition called

caput medusae Caput medusae is the appearance of distended and engorged superficial epigastric veins, which are seen radiating from the umbilicus across the abdomen. The name ''caput medusae'' (Latin for "head of Medusa") originates from the apparent simil ...

Catheterization

A newborn baby has a patent umbilical vein for at least a week after birth. This umbilical vein may be catheterised for ready intravenous access. It may be used as a site for regular transfusion in cases of erythroblastosis or

hemolytic disease Hemolytic anemia or haemolytic anaemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells (RBCs), either in the blood vessels (intravascular hemolysis) or elsewhere in the human body (extravascular). This most commonl ...

. It also provides a route for measuring central venous pressure.

Additional images

File:Gray31.png, Model of human embryo, 1.3 mm. long. File:Gray39.png, Scheme of placental circulation. File:Gray458.png, Diagram of the vascular channels in a human embryo of the second week. File:Gray476.png, Human embryo with heart and anterior body-wall removed to show the

sinus venosus The sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the chordate heart. In mammals, the sinus venosus exists distinctly only in the embryonic heart where it is found between the two venae cavae; i ...

and its tributaries. File:Gray989.png, Schematic figure of the

lesser sac The lesser sac, also known as the omental bursa, is a part of the peritoneal cavity that is formed by the lesser omentum, lesser and greater omentum. Usually found in mammals, it is connected with the greater sac via the omental foramen or ''For ...

, etc. Human embryo of eight weeks. File:Gray1088.png, Liver with the

septum transversum The septum transversum is a thick mass of cranial mesenchyme, formed in the embryo, that gives rise to parts of the thoracic diaphragm and the ventral mesentery of the foregut in the developed human being and other mammals. Origins The septum t ...

. Human embryo, 3 mm. long. File:Gray475.png, Sketch of the vessels in a human embryo of the third week. File:Gray1115.png, Tail end of human embryo, twenty-five to twenty-nine days old. File:Umbilical vein.jpg, Umbilical vein File:Slide1MINI.JPG, Human embryo, 38 mm, 8–9 weeks.

References

External links

* {{DEFAULTSORT:Umbilical Vein Embryology of cardiovascular system Veins