Scientific Proceedings. 



85 



57 (200) 



A series of spontaneous tumors in mice. 



By E. E. TYZZER. 



\_From the Laboratory of the Caroline Brewer Croft Cancer Com- 

 mission, Harvard Medical School, .] 



In the investigation of tumors in mice, attention has been, for 

 the most part, directed to those which develop in the subcutaneous 

 tissue. It is possible that internal tumors often occur unnoticed. 

 In this series the tumors of the lung are most frequent. 



Primary, papillary, cyst-adenomata of the lung have been 

 found in eleven cases. All these tumors conform to one type, 

 and consist of cuboidal or columnar epithelium covering irregular 

 folds and processes of connective tissue. No mitotic figures have 

 been found in the epithelium of these tumors, so that it is evident 

 that they are not rapidly growing. Most of these tumors were 

 very minute and in several instances, when they occurred with 

 other primary tumors, they were mistaken for metastases until 

 examined histologically. In one case a tumor of this type attained 

 such size that it filled about one third of the thorax. In two 

 other cases tumors were found growing into the bronchi. These 

 tumors occur in both male and female, and appear to be about 

 equally frequent in the inoculated and non-inoculated mice. The 

 largest of the lung tumors was inoculated into five mice, but failed 

 to develop further. 



Minute adenomata of the kidney were found in two cases. 



A rapidly growing lympho-sarcoma, which occurred in an old 

 female mouse, was inoculated into seventeen mice with negative 

 results. 



Tumors of the mammary gland have developed in three old 

 female mice, and in each case the lymphatics were invaded by the 

 growth. In the first case the primary tumor presents, in addition 

 to simple adenoma, transitions from this to an actively growing 

 carcinoma. Another adeno-carcinoma of the mammary gland 

 occurred in a waltzing mouse. The tumor is peculiar in that 

 groups of the epithelial cells become vacuolated, and resemble 

 very closely the sebaceous glands of the skin. The inoculation 



