ESOPHAGUS, STOMACH AND INTESTINE 



171 



tinal tube expands to form the cloaca. It is supported from the dorsal body 

 wall by the mesentery (Fig. 178). 



From 5 to 9 mm. the ventral bend of the intestinal loop becomes more marked 

 and the attachment of the yolk stalk to it normally disappears (Fig. 179). 



Tongue 



Rathke's 

 pouch 



Liiryngfllracheal 

 groove 



■u — L. lung 



^^M- Stomach 



Sj — Liver 



Dorsal 

 pancreas 



Melane phros 



Mesonephric 



Fig. 178. — Reconstruction of a 5 mm. human embryo showing the entodermal canal and its derivatives 



(His in KoUmann). X 25. 



The attachment of the yolk stalk may persist in later stages (12 to 14 mm. embryos, 

 according to Keibel, Elze, and Thyng). Also in 2 per cent, of adult intestines a pouch 3 to 9 

 cm. long is found about 80 cm. above the colic valve, where the yolk stalk was formerly 

 attached. This pouch, the diverticulum of the ileum or Meckel's diverticulum, is of clinical 

 importance as it may cause intestinal strangulation in infants. 



At the stage shown in Fig. 179, the dorsal pancreatic anlage has been de- 

 veloped from the duodenum, and, in the caudal hmb of the intestinal loop, there 



