192 THE ENTODERMAL CANAL AND THE BODY CAVITIES 



have seen (p. 179) that the cranial portion of the ventral mesentery forms the 

 mesocardium of the heart. In the ventral mesentery caudal to the septum trans- 

 versum the Hver develops. From the first, it is enveloped in folds of the splanch- 

 nic mesoderm which give rise to its capsule and ligaments as the liver increases 

 in size (Fig. 190 B). Wherever the hver is unattached, the mesodermal layers 

 of the ventral mesentery form its capsule (of Ghsson), a fibrous layer covered 

 by mesothehum, continuous with that of the peritoneum (Fig. 190 B). Along 

 its mid-dorsal and mid-ventral hne the hver remains attached to the ventral 

 mesentery. The dorsal attachment between the hver, stomach, and duodenum 

 is the lesser omentum. Tliis in the adult is differentiated into the duodeno-hepatic 

 and gastro-hepatic Hgaments. The attachment of the hver to the ventral body 

 wall extends caudally to the umbihcus and forms the falciform ligament. 



In its early development the liver abuts upon the septum transversum, and 

 in 4 to 5 mm. embryos is attached to it along its cephaHc and ventral surfaces. 

 Soon dorsal prolongations of the lateral hver lobes, the coronary appendages, 

 come into relation with the septum dorsally and lateraUy. The attachment of 

 the hver to the septum transversum now has the form of a crescent, the dorsal 

 horns of which are the coronary appendages (Fig. 200). This attachment be- 

 comes the coronary ligament of the adult hver. The dorso-ventral extent of the 

 coronary hgament is reduced during development and its lateral extensions upon 

 the diaphragm give rise to the triangular ligaments of each side. 



The right lobe of the hver, as we have seen, comes into relation along its 

 dorsal surface with the plica venw cava in 9 mm. embryos (Figs. 199 and 200). 

 This attachment extends the coronary Hgament caudally on the right side and 

 makes possible the connection between the veins of the hver and mesonephros 

 which contributes to the formation of the inferior vena cava. The portion of the 

 hver included between the phca venae cavEe and the lesser omentum is the caudate 

 lobe (of Spigehus). 



In a fetus of five months the triangular ligaments mark the position of the 

 former lateral coronary appendages. The umbihcal vein courses in a deep groove 

 along the ventral surface of the liver, and, with the portal vein and gall bladder, 

 bounds the quadrate lobe. 



Changes in the Dorsal Mesentery.— Tha.t part of the digestive canal which 

 hes within the peritoneal cavity is suspended by the dorsal mesentery, which at 

 first forms a simple attachment extending in the median sagittal plane between 

 body wall and primitive gut. That portion of it connected with the stomach 

 forms the greater omentum, the differentiation of which has been described (p. 191). 



