PANCREAS OF MAMMALIA. 



497 



381 



Pancreas, exposed by raising the stomach ; Human. 



CXLVIII". 



! 



+1 



the detached condition which prevails in some lower mammals : the 

 splenic portion, ib. pa, contracts near the spleen, sp. The thick 

 upper border receives in a groove or canal the splenic artery and 

 vein. The main duct tra- 

 verses the substance of the 

 gland nearer the lower than 

 the upper border ; it is com- 

 monly joined near its end 

 by the duct from the lesser 

 pancreas, or ( head,' h : but 

 the homology of this with the 

 duodenal pancreas of lower 

 mammals and birds is some- 

 times instructively exempli- 

 fied by the independent 

 entry of its duct into the 

 duodenum, as in fig. 382, b, 

 c. In the ordinary arrangement the duct ot the larger, b, unites 

 with that of the lesser pancreas, and the common pancreatic duct 

 penetrating the duodenal tunics joins the common bile-duct at the 

 ampulla, before entering the intestine, as shown in fig. 376. In the 

 variety B, the duct of the larger 

 pancreas, b, alone has this rela- 

 tion with the gall-duct, a . : in a 

 rarer variety, c, the common 

 duct of the pancreas, b, opens 

 distinctly from the common 

 bile-duct, a: in a still rarer 

 anomaly, D, the duct of the 

 lesser pancreas receives tribu- 

 taries from the larger pancreas, 

 becoming a tube of equal size, 

 and the two, b, c, unite, before 

 the usual junction with the bile- 

 duct, a. The proper coat of 

 the pancreatic duct is a firm 

 tissue of interwoven, mainly 

 longitudinal, fibres ; with an 

 outer loose areolar covering and 



382 



Varieties in the termination of the pancreatic duct 

 Man. ccxxxi. 



n epithelial lining. This, in 

 the minute beginnings of the carrying system, consists of co- 

 lumnar cells so packed that their ends next the duct-cavity pre- 

 sent a penta- or hexa-gonal pavement, fig. 383. The initial ductlets 

 arise from the interspaces of the follicular or cell-structure of the 



VOL. Ill, K K 



