COELOM AND MESENTERIES 537 



It is this same closure of the ventral body walls which also brings 

 the two portions of the gut together ventrally. This causes the newly- 

 closed gut to lie between the two layers of splanchnic mesoderm while 

 the body-spaces on each side form a right and left coelomic chamber. 

 In fact, there are double layers of mesoderm which enclose and support 

 the gut. These double layered supports are called mesenteries. The 

 dorsal mesentery remains as a continuous support at least the greater 

 portion of it does but the ventral mesentery soon disappears, causing 

 the right and left coelomic cavities to become confluent. 



In the liver region, however, the ventral mesentery does not dis- 

 appear (Fig. 293). The liver arose by a ventral outgrowth of the gut 

 and extended into the ventral mesentery. As the liver grows ventrally 

 from the digestive tract, there is a portion of the ventral mesentery lying 

 dorsal to the liver, that is, between the liver and the gut. This persists 

 as the gastro-hepatic amentum while the portion ventral to the liver is 

 called the ventral ligament or the falciform ligament. 



The dorsal mesentery persists, as stated, but has different names in 

 different parts, i. e., mesocolon, where it supports the colon, mesogaster, 

 where it supports the stomach, etc. 



Septa grow out from the body wall to divide the body-cavity into 

 the pericardial, pleural, and peritoneal chambers mentioned above. 



