SPONTANEOUS NEOPLASMS IN MICE 



211 



This type contains very little stroma except for numerous small, endothelial 

 lined, capillary-like blood vessels. The outlines of the tumor cells may be 

 vague but suggest round and polyhedral shapes. They have irregular, oval, 

 hypochromatic nuclei and the cytoplasm is filled with rather deeply staining 





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Fig. ii6. — Primary papillary adenocarcinoma of the lung (X200). This tumor 

 is sub-pleural and has been invaded by metastatic carcinoma of the mammary gland 

 (lower left on the illustration). 1., lung; m.m., metastatic mammary gland carcinoma; 

 p.l., primary lung carcinoma; str., stroma. 



eosinophilic granules. Sometimes the cytoplasm is reduced in amount, 

 nuclei vary in size and have prominent nucleoli. These cells show no defi- 

 nite arrangement and are accompanied by more stroma than the above. 

 The undifferentiated tumor cells may blend with definite papillary adeno- 

 carcinoma. This tumor shows abundant mitotic figures and may develop 

 widespread metastases. 



