MAST CELLS IN CATTLE AND RAT 



the capsules of kidney, thyroid, thymus and adrenal are examined, and it hardly 

 explains the association of mast cells with the connective tissue generally. 



Kidney capsule forms an interesting comparison with the capsules described 

 above, in that the true capsule of the kidney is separated from the overlying 

 peritoneum by a thick pad of loose perinephric fat and connective tissue. 

 Nevertheless, a tissue spread of kidney capsule shows it to contain a high content 



Fig. 4 

 Tissue spread ox tendon sheath. Many mast cells, singly or in pairs, are scattered over the 



serous surface ( : 140). 



of mast cells (Fig. 8). In contrast, mast cells are entirely lacking in the kidney 

 parenchyma, though they are again seen in the subepithelial connective tissue 

 of the kidney pelvis and remain plentiful in this type of tissue throughout the 

 urogenital tract. Mast cells also occur in the capsules of organs which are 

 unrelated to the serous membranes: they are common in the loose connective 

 tissue which surrounds the thyroid and the adrenals and in the capsule and 

 trabeculae of the thymus. Indeed, mast cells are demonstrable in all the loose 

 fibrillary connective tissue in cattle: this includes the dermis and subcutis, 

 the loose intermuscular connective tissue of both voluntary and involuntary 

 muscles and the subsynovial and pericapsular connective tissue of joints. 

 Tissue of similar appearance can be traced in continuity from the pericardium 



43 



