214 



PHYSIOLOGY 



CHAP. 



FIG. 72. Dog's bile-duct obtained by 

 maceration with nitro-glycerin. Macro- 

 scopic view. (Oddi.) a, 6, plain 

 circular fibres of sphincter .of bile-duct 

 at the point at which it passes through 

 the coats of the intestine. 



collects in the gall-bladder during abstinence, and is poured out 

 into the duodenum by the common bile-duct during digestion ? 

 In 1887 Oddi, with the object of determining the functional 



importance of the gall-bladder, at- 

 tempted to produce a continuous 

 flow of bile into the intestine by 

 completely removing the gall- 

 bladder in dogs, an operation pre- 

 viously performed by Zambeccari, as 

 suggested by Galileo. The animals 

 operated on recovered quickly, 

 without exhibiting abnormal pheno- 

 mena of any significance. But the 

 sections made some time after si i owed 

 the hepatic duct, cystic duct, and 

 common bile-duct to be dilated to 

 twice or even three times their 

 normal calibre. The cystic duct, in 



fact, seemed to be transformed into a reservoir for the bile, and 

 had the appearance of a newly formed gall-bladder. This experi- 

 ment has been utilised in surgery, since in cases of stones in the 

 gall-bladder (producing severe 

 colic) it is possible successfully 

 to open, empty, and excise the 

 gall - bladder abnormally dis- 

 tended by the presence of 

 calculi. To explain these re- 

 sults it must, of course, be 

 assumed that in animals de- 

 prived of their gall-bladder a 

 powerful obstacle is opposed to 

 the continuous outpouring of 

 bile, and promotes the marked 

 dilatation observed in the bile- 

 ducts. 



This legitimate assumption 

 led Oddi directly to the dis- 

 covery of a special sphincter of 

 plain muscle, situated at the 

 duodenal end of the common 

 bile-duct, a sphincter which is 

 entirely independent of the 

 muscular coat of the intestine. 



It is visible even to the naked eye in some animals (sheep, dog, 

 ox, pig), in which the bile-duct, before opening into the duodenum, 

 runs for a certain distance between the muscular coats of the 

 intestine (Fig. 72). In sheep and dogs, owing to the robust nature 



FIG. 73. Sections of intestine transverse to axis 

 of bile-duct, A, of sheep ; B, of man. Carmine 

 preparation. (Oddi.) a, b, sphincters of bile- 

 duct ; rf, muscular fibres of intestine, indepen- 

 dent of fibres of sphincter. 





