1248 



THE ORGANS OF DIGESTION 



In its course from the head to the tail the primitive alimentary canal is held 

 to the body axis (notochord) by a broad mass of mesoderm, from which the common 



Rathke's pouch 

 Notochord. (pituitary involution). 



Lung diver-, 

 ticulum. 

 Stomach. 



Liver. 



Opening into, 

 yolk sac. 



Allantois.- 1- - 



_ \ Terminal portion of 

 hi itd-gut. 



-Wolffian duct. 



I,ung diverticulum 

 (Esophagus. ^ 



Median rudiment of 

 / thyroid gland. 

 I -Mandibular arch. 

 ;Notochord. 



Rathke's 

 pouch 

 (pituitary 

 involution). 



Omphalo- 



mesenteric 



duct*. 



Allantois. -~\ 



Terminal portion of 

 hind-gut. 



-/-Wolffian duct. 



FIGS. 966 and 967. Sketches in profile of two stages in the development of the human alimentary canal. 



Fig. 966 X 30. Fig. 967 X 20. (His.) 



mesentery of the gut is subsequently developed. The foregut 1 is also held by 

 a ventral mesentery, the thoracic portion of which becomes modified by the de- 



1 The junction of the foregut with the midgut is generally understood to be at the level of the orifice of the 

 common bile duct, or site of origin of the liver diverticulum. 



