MAST CELLS IN CATTLE AND RAT 



along the great vessels (especially the veins) down to the smallest arterioles 

 and venules, around which it forms their adventitial sheath. 



Such loose connective tissue is also common in the wall of the gut, filling 

 the spaces between the deeper portions of the glands and forming the under- 

 lying submucosa. Enormous numbers of mast cells can be demonstrated in 

 any section of the complex gastric organ of cattle. In the submucosa of the 



Fig. 7 



Tissue spread, calf liver capsule. The mast cells are fewer and less well granulated than in the 



adult ( 168). 



small intestine the cells are concentrated especially around non-encapsulated 

 lymphoid nodules: where such a nodule is cut tangentially the appearances 

 suggest a solid focus of mast cells. Their presence under the investing layer of 

 peritoneum has been described above. 



Mast cells are not common in lymph nodes proper and do not occur in 

 cartilage (ear and trachea), in mature collagen (tendo achilles) or in mature 

 elastic tissue (ligamentum nuchae). Nor are they seen within the central 

 nervous system, though they are common in the dura mater and the connective 

 tissue sheaths of peripheral nerves and occur also around the blood vessels 

 of the choroid plexuses. 



This survey of the tissue mast cells in cattle thus emphasizes more their 



45 



