TUMORS. 



329 



tiple. They may occur in the wall of the gastro-intestinal canal, and 

 have been seen in the kidney, in the bladder, and in the skin. The so- 



FIG. 173. MYOMA OF THE UTERUS. 

 This is of the smooth muscle type leiomyoma and shows one bundle of muscle cells cut lengthwise, others 



^^VS^'v^WV 



?.S***^} 



called hypertrophies of the prostate, so frequent in advanced life, are 



sometimes considered leiomyomata of the interstitial muscle tissue of that 



gland. 



II. Myoma Striocellulare, or Ehabdomyoma. In these rare tumors 



striated muscle fibres are the characteristic elements. They very rarely 



compose a great part of the tumor, 

 but are intermingled with other ele- 

 ments, fibrillar connective tissue, 

 spindle-shaped and spheroidal cells of 

 various forms, which often appear to 

 l>e incompletely developed muscle 

 cells. They are not infrequently 

 associated with sarcomatous tissue. 

 Blood-vessels and sometimes nerves 

 are also present. The muscle fibres 

 differ, as a rule, from normal striated 

 muscle fibres in their arrangement, 

 which is usually quite irregular, and 

 also in size, being in general smaller 

 than normal fibres, although varying 

 greatly. The sarcolemma is either 

 absent or incompletely developed. 

 These tumors are usually small or 

 of moderate size, and are supposed to 

 originate from' inclusions of cells 

 destined to form muscle tissue in 

 places where they do not belong. 

 In the heart and certain other muscular parts small circumscribed 



masses of striated muscle tissue have been described, and are sometimes 



FIG. 174. FIBRO-MYOMA or UTEIHS. 



The muscle cells are crowded apart by dense 

 fibrous tissue. 



