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THE ENTODERMAL CANAL AND THE BODY CAVITIES 



The Omental Bursa or Lesser Peritoneal Sac. According to Broman, 

 the omental bursa is represented in 3 mm. embryos by a peritoneal pocket 

 which extends cranially into the dorsal mesentery, to the right of the 

 esophagus. A similar pocket present on the left side has disappeared in 

 4 mm. embryos. Lateral to the opening of the primitive lesser peritoneal 

 sac, a lip-like fold of the mesentery is continued caudally along the dorsal 



Body wall 



Falciform ligament 



Coronary attachment of 

 liver to diaphragm 



Inferior vena cava 



Sup. recess of lesser 

 peritoneal sac 



Pleura- peritoneal 

 membrane 



Inferior vena cava 

 Plica vena caves 



Mesonephric fold 

 Genital fold 



Greater amentum 



Spleen 



Stomach 



Lesser peritoneal sac 

 Aorta 



FIG. 200. A diagrammatic ventral view of the middle third of a human embryo, 12 to 15 

 mm. long. The figure shows the caudal surface of a section through the stomach and spleen, 

 a ventral view of the stomach, the liver having been cut away to leave the sectioned edges of the 

 lesser omentum and. plica venae cavae, and the caudal surface of the septum transversum and 

 pleuro-peritoneal membrane. Upon the surface of the septum is indicated diagrammatically 

 the attachment of the liver. (Based on figures of Mall and F. T. Lewis and model by H. C. 

 Tracy.) 



body wall into the mesonephric fold as the plica vena cavae, in which the 

 inferior vena cava later develops (Fig. 199). The liver, it will be remem- 

 bered, grows out into the ventral mesentery from the fore-gut, and, ex- 

 panding laterally and ventrally, takes the form of a cresent. Its right 

 lobe comes into relation with the plica venae cavae, and, growing rapidly 

 caudad, forms with the plica a partition between the lesser sac and the 



