THE GALL BLADDER 



335 



are circularly disposed. Occasionally they form fairly distinct cir- 

 cular and longitudinal layers. 



The fibro-serous coat consists of loose areolar tissue, which con- 

 tains the larger blood vessels with which the organ is abundantly 

 supplied. The free surface of the gall bladder also receives a 

 peritoneal investment. 



FIG. 278. KECONSTRUCTION OF THE WALL OF A DOG'S GALL BLADDER. 

 a, vein ; 6, artery ; c, lymphatic vessel ; d, epithelium, x 60. (After Sudler.) 



Occasional mucous glands occur in the mucosa of the gall 

 bladder. These are mostly of small size and widely separated, but 

 toward the neck of the organ they increase in both number and 

 size. They form short, branched, convoluted tubules. 



The blood vessels form a plexus just outside the muscular coat, 

 from which branches are distributed to the peritoneal coat and to 

 a plexus in the depth of the mucosa from which capillaries are 

 supplied to the muscular layers and to a subepithelial plexus. 

 The nerves are distributed to the blood vessels and to the mus- 

 cular wall. Minute ganglia occur in the muscular coat. 



