| Embryonic Liver Development Timeline
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| This information is from a recent study[1] of the human embryonic liver from week 5 to 8 (GA 7 to 9; Carnegie stage 14 to 23).
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| Carnegie Stage
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Age
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CRL (mm)
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Biliary system
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Vascular
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Hepatic parenchyma
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| 14
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33
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7
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- Primordial bile duct (links primitive intestine and liver parenchyma) visible. Thick-walled tube (95 µm diameter) with a small lumen (22 µm in diameter).
- Gallbladder - elongated tube further dilated, thick wall (125 µm in diameter) and a narrow lumen (43 µm of diameter).
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- Intra-hepatic vasculature is represented by the presence of hepatic sinusoids.
- Three venous tributaries flow into the liver sinusoids: a large right umbilical vein, a large left placental vein and a single vitelline vein.
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- Cords of liver cells are fragmented by vascular network of the hepatic sinusoids.
- Located between the pericardial cavity at the top and the mesonephros at the bottom.
- Upper pole of the liver lies close to the septum transversum and early ventricles.
- Liver occupies the majority of abdominal cavity.
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| 18
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46
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15
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- Bile duct (future common bile duct), and a common hepatic duct, which is in contact with the liver parenchyma without penetration.
- Primordium of accessory bile tract is an elongated and fusiform gall bladder projecting forward and by a short cystic duct that opens into the common bile duct.
- The bile duct empties into the second part of duodenum on its posterior side.
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- Portal system visible - portal vein (100 µm diameter) arises from the connection of the upper mesenteric vein then at region of the hepatic hilum (285 µm) divides into portal branches.
- Left umbilical vein empties into the anterior extremity of the left portal branch.
- Ductus venosus (80 µm) connects the initial portion of left portal vein to the inferior vena cava.
- Hepatic venous system 3 branches - left hepatic vein (120 µm in diameter), middle hepatic vein (220 µm in diameter) and right hepatic vein (160 µm in diameter). Flows into the sub-cardinal vein.
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- Liver parenchyma has two anatomical lobes, a right lobe and a left lobe, separated by the anteroposterior plane formed by the placental vein.
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| 21
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53
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22.5
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Bile duct morphology as earlier stage. Common bile duct empties at the level of the proximal duodenum.
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- Portal vein arises from the joining of the splenic vein and the superior mesenteric vein. At the level of the hepatic hilum, portal vein divides into two branches, right portal branch (420 µm in diameter) and left portal branch (540 m in diameter). Right portal branch gives rise to a thin branch to the caudate lobe. Ventral branch gives rise to segmental portal veins (VIII and V). Dorsal branch gives rise to the segmental portal veins (VI and VII).
- Ductus venosus connects the initial portion of the left portal vein to the inferior vena cava just upstream from the hepatic vein afferents.
- Hepatic venous system as for previous stage.
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Hepatic parenchyma looks like a large rounded mass.
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| 23
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58
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27
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Bile duct morphology as earlier stage.
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- Portal venous system complete.
- Ductus venosus (40 m) connects the initial portion of the portal vein to the middle hepatic vein.
- hepatic venous system has changed very little from the previous stage. the three hepatic veins empty into the inferior vena cava.
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- Liver parenchyma has a roughly oval shape. Two symmetrical hepatic lobes are identifiable. The quadrate and caudate lobes are identifiable.
- Upper pole of the liver is always bounded above by the diaphragm.
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| Links: Liver Development
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