SPONTANEOUS NEOPLASMS IN MICE 



227 

 The 



blood vessel invasion occurs and metastases in the liver are seen. 

 ovaries are sometimes involved by extension of this tumor. 



Leiomvosarcoma is a tumor which is grossly like fibrosarcoma but micro- 

 scopically is composed of larger, longer spindle cells. These cells are 

 arranged in irregular interlacing bundles and arc of the smooth muscle type 

 characteristic of the uterine wall. Mitoses are not frequent. 



Fig. 124. — Primary tumors of the uterus. A, carcinoma simplex that originated 

 in the uterine epithelium and invaded the uterine wall (X200); B, fibrosarcoma in the 

 wall of the uterus (X200). car., carcinoma simplex; ep., epithelium; n.u.w., normal 

 uterine wall; sar., fibrosarcoma. 



Other tumor forms seen include adenofibrosarcoma, hemangioma and 

 hemangio-endothelioma. All these are rare. The first shows a few uterine 

 glands deep within a fibrosarcoma. The third type has been seen but once 

 and was in the oviduct. 



Tumors of the Testes 



Tumors are rare at this site. Slye (55) reported 28 primar}' tumors in 

 the testes of mice. The majority of her tumors appear to be similar to two 

 cases that we have called embryonal cell carcinoma. These tumors show- 

 many of the characteristics described by her. The tumor cells are large, 

 rounded and pale with abundant cytoplasm and hypochromatic nuclei 



