276 



HUMAN EMBRYOLOGY AND MORPHOLOGY. 



toneum, both layers subsequently being absorbed. Thus the 

 descending meso-colon, originally situated in the middle line, 

 comes to be attached in the left lumbar region. 



spl. plex. colon 



left col. art. 

 inf. mes. 

 sigmoid 



mid. colic 



duoden'. 



uctsct intest. ten. 

 pre-art. mesent. 



ileo-col. art, 

 post. art. mesent. 



Meckel's diuert. 



A. 



left kidney 



^periton. 

 ,iesoZlon^ desc - co,or > 



ab. aorta 



B. 



Fig. 223 X — The mesentery of the hind-gut. The Position assumed by the Colon 



after the rotation of the Gut has taken place. 

 Fig. 223 B. — Diagram to show how the descending Meso-colon becomes applied to the 



parietal Peritoneum of the left Lumbar Region. 



The Intersigmoid. Fossa. — The sigmoid flexure, after the 

 rotation of the gut, forms a loop, with its convexity directed 

 towards the liver. The meso-sigmoid is originally attached in 

 the middle line, but the pressure of the developing loop of small 

 bowel pushes the meso-sigmoid against the posterior abdominal 

 wall and left iliac fossa. The extent to which it adheres varies ; it 

 may become completely adherent like the descending meso-colon, 



