TUMORS. 



Z27 



arranged in a single layer, although the tubules or acini may he 

 entirely filled with cells arranged layer upon layer. The type 

 of cells adheres to the description given in discussing carcinoma. 

 The stroma is usually composed of fibrous connective tissue 

 and IS variable in amount. Blood vessels are found within the 

 stroma. The cells lining the acini may be active and the secre- 

 tion is frequently retained, thus resulting in a cvst-adenoma. 

 The accumulated secretion may cause degeneration of the stroma, 

 and the acini rupturing one into another produce a large cvst. 



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Fig. ISO. — Section of an Adenoma fivim tht- frontal sinus of a mult 

 the arrangement of tumor tissue into acini and tubules. 



Clinically these tumors, as a class, are malignant, l)Ut do not 

 produce fatal results as rapidly as carcinomata. Many individ- 

 ual adenomata are benign. A horse's tail was recently ampu- 

 tated that for three years had been affected with an adenoma of 

 the sebaceous glands. IK bitch affected with an adenoma of the 

 mammary gland has been under observation for two years and 

 is normal except for the presence of the tumor. These tumors 

 rarelv recur when removed. From experience it has been found 

 that mammary adenomata of the bitch usually result fatally im- 

 pnr~ri;ote!v after operation. (The operation appears to produce 



