Liver with the septum transversum. Human embryo 3 mm. long.
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|Latin
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|colspan="2"|[subject #250 ]
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|System
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|Carnegie stage
|colspan="2"|[10]
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|Days
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|Precursor
|colspan="2"|mesenchyme
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|Gives rise to
|colspan="2"|diaphragm
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|MeSH
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|Dorlands/Elsevier
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The liver arises in the form of a diverticulum or hollow outgrowth from the ventral surface of that portion of the gut which afterward becomes the descending part of the duodenum.
This diverticulum is lined by entoderm, and grows upward and forward into the septum transversum, a mass of mesoderm between the vitelline duct and the pericardial cavity, and there gives off two solid buds of cells which represent the right and the left lobes of the liver.
Between the two latter diverticula is a mass of mesoderm containing the ducts of Cuvier, and this is continuous ventrally with the mesoderm in which the umbilical veins are passing to the sinus venosus.
A septum of mesoderm thus extends across the body of the embryo.
It is attached in front to the body-wall between the pericardium and umbilicus; behind to the body-wall at the level of the second cervical segment; laterally it is deficient where the pericardial and pleuro-peritoneal cavities communicate, while it is perforated in the middle line by the foregut.
This partition is termed the septum transversum, and is at first a bulky plate of tissue.
