228 



BIOLOGY OF THE LABORATORY MOUSE 



containing coarse chromatin granules. Some nuclei are vesicular. Mitotic 

 figures are quite numerous. The architecture shows cords and dense 

 masses of epithelial cells without much stroma. One of our cases appeared 

 in the I stock and the other in the black-eved white (AMC) stock. 



b.v. 





'>;c^^ 











Fig. 125. — Carcinoma simplex of the uterus (X400). b.v., Ijlood vessel; car., car- 

 cinoma simplex; e.p., epithelium grading over into carcinoma; u.l., uterine lumen. 



No other types of tumors of the male reproductive organs have been 

 found in our stocks. Slye reported sarcomas found in the testicle and in 

 the seminal vesicle. 



Tumors or the Central Nervous System 



Brain tumors. — These neoplasms are rarely found in mice. We have 

 observed a medulloblastoma (Fig. 126). Another tumor has been diagnosed 

 as a glioma. Both of these were in C57 black females. It is of interest that 

 in this same stock hydrocephaly has been observed in a number of young of 



