Obliteration
Generally, the duct fully obliterates (narrows and disappears) during the 5-6th 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. About two percent 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.
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