Vitelline duct 4472292 219919382 2008-06-17T13:29:55Z Uwe Gille 211241 +de, es removed (describes yolk sac) {{Infobox Embryology | Name = {{PAGENAME}} | Latin = | GraySubject = 10 | GrayPage = 54 | Image = Gray30.png | Caption = [[Fetus]] of about eight weeks, enclosed in the [[amnion]]. (Vitelline duct labeled at lower right.) | Image2 = Gray982.png | Caption2 = Sketches in profile of two stages in the development of the human digestive tube. (Vitelline duct labeled on bottom image.) | System = | CarnegieStage = | Days = 28 | Precursor = [[midgut]], [[yolk sac]] | GivesRiseTo = | MeshName = Vitelline+Duct | MeshNumber = A16.254.891 | DorlandsPre = | DorlandsSuf = | }} At the end of the fourth week the [[yolk-sac]] presents the appearance of a small pear-shaped vesicle (umbilical vesicle) opening into the digestive tube by a long narrow tube, the '''vitelline duct''', also known as the omphalomesenteric duct. The vesicle can be seen in the [[after-birth]] as a small, somewhat oval-shaped body whose diameter 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]]. As a rule the duct undergoes complete obliteration during the seventh week, but in about two per cent of cases its proximal part persists as a diverticulum 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]]. Sometimes a narrowing of the [[lumen]] of the [[ileum]] is seen opposite the site of attachment of the duct. ==Additional images== <gallery> Image:Gray983.png|Front view of two successive stages in the development of the digestive tube. </gallery> ==External links== * {{eMedicineDictionary|yolk+stalk}} {{Embryology}}[[Category:Embryology]] [[de:Dottergang]]