THE DIGESTIVE SYSTEM 55 



arrangement found in the mammalian liver, 

 nor are the outlines of the individual cells 

 easily distinguished. The liver of the young 

 chick, however, consists of anastomosing 

 tubules, lined with cubical cells surrounding 

 a narrow lumen (Fig. 27). Between the tubules 

 are blood-spaces or sinusoids connected with 

 larger vessels arranged in a more or less radial 

 manner. 



An elongated, thin, lobulated, and pale- 

 yellow or reddish pancreas occupies the narrow 

 interval between the two limbs of the 

 duodenum (Figs. 12, 15, and 22). Two, or 

 possibly more generally three, ducts carry 

 the secretion of the gland into the ascending 

 duodenal limb, where they open close beside 

 the bile ducts. In structure the pancreas is 

 a typical lobulated gland, with a framework 

 of connective tissue supporting the secreting 

 alveoli and the ducts by which the secretion 

 is carried away. The alveoli are short 

 tubules lined by a layer of granular epithelial 

 cells surrounding a lumen of small diameter 

 (Fig. 28). Small ducts, lined by low epi- 

 thelium, are continuous with the mouths of 

 the alveoli and join larger ducts in which the 

 epithelium is taller. By repeated union the 



