| Vitelline duct | |
|---|---|
| Fetus of about eight weeks, enclosed in the amnion. (Vitelline duct labeled at lower right.) | |
| Sketches in profile of two stages in the development of the human digestive tube. (Vitelline duct labeled on bottom image.) | |
| Gray's | subject #10 54 |
| Days | 28 |
| Precursor | midgut, yolk sac |
| MeSH | Vitelline+Duct |
In the human embryo, the vitelline duct, also known as the omphalomesenteric duct, is a long narrow tube that joins the yolk sac to the midgut lumen of the developing fetus.[1] It appears at the end of the fourth week, when the yolk sac presents the appearance of a small pear-shaped vesicle (the umbilical vesicle).
Contents |
Generally, the duct fully obliterates (narrows and disappears) during the 7th week of fertilization age (9th week of gestational age), but a failure of the duct to close is termed a vitelline fistula. This results in discharge of meconium from the umbilicus.[2] About two per cent of fetuses exhibit a type of vitelline fistula characterized by persistence of the proximal part of the vitelline duct as a diverticulum protruding from the small intestine, Meckel's diverticulum, which is situated about two feet above the ileocecal junction and may be attached by a fibrous cord to the abdominal wall at the umbilicus.
The vesicle can be seen in the afterbirth as a small, somewhat oval-shaped body, the diameter of which varies from 1 mm to 5 mm. It is situated between the amnion and the chorion and may lie on or at a varying distance from the placenta.
Sometimes a narrowing of the lumen of the ileum is seen opposite the site of attachment of the duct.
A mnemonic used to recall details of a Meckel's diverticulum is as follows: "2 inches long, 2 feet from ileocecal valve, 2% of population, 2% symptomatic, 2 types of ectopic tissue: gastric and pancreatic."
|
|||||||||||||||||||||||