302 



EMBRYOLOGY. 



The duodenum, describing the well-known horseshoe-shaped curve,, 

 applies its mesentery, in which the beginning of the pancreas is en- 

 closed, broadly to the posterior wall of the body, and fuses throughout 

 its whole extent with the peritoneum of the latter; from being 

 a movable it has become an immovable portion of the intestine 

 (fig. 167 du). 



The large intestine (figs. 165 and 167-4 and B ct) still possesses in 

 the third month a very broad suspensorium arising from the vertebral 

 column, which is nothing else than a part of the common mesentery 



Fig. 167 A B. Two diagrams to illustrate the development of the bursa omentalis. 



A, earlier, J5, later stage. 



zf, Diaphragm ; I, liver ; p, pancreas ; mg, stomach ; gc, its greater curvature ; du, duodenum ; 

 dd, small intestine; ct,- colon transversum ; *, bursa omentalis; kn, lesser omentum ; 

 gn\ posterior [dorsal] lamella of the greater omentum, arising from the vertebral column ; 

 gri>, anterior [ventral] lamella of the same, attached to the greater curvature of the stomach 

 (gc) ; gn 3 , the part of the omentum which has grown over the small intestine ; gn*, the 

 part of the omentum which encloses the pancreas ; mes, mesentery of the small intestine * 

 msc, mesocolon of the transverse colon. 



of the intestine, but which has received the special designation of 

 mesocolon (msc). In consequence of the previously described twisting 

 of the primitive loop of the intestine, not only the colon trans- 

 versum, but also the considerable mesocolon belonging to it, has been 

 drawn transversely across the end of the duodenum ; for a certain 

 distance it fuses with the latter and with the posterior wall of the 

 body, thereby acquires a new secondary line of attachment (fig. 167 

 msc) running from right to left, and thus appears as a part that has 

 become detached from the.common mesentery. The colon transversum 

 (ct) with its mesocolon (msc) now divides the body-cavity into an 



