SPONTANEOUS NEOPLASMS IN MICE 225 



cells which show foci that appear almost sarcomatous. Probably at least 

 part of the latter are from theca interna cells. In the ce stock, at least, 

 large clusters of Sertoli-Hke cells are often encountered with the last men- 

 tioned form of tumor cells. The large, clear, lutein-like cells seen by J. 

 Furth and Butterworth (16) have not been found as the type cell of any 

 of our spontaneous ovarian tumors. However, MacDowell-Bagg stock 

 albinos treated with x-ray have produced several, and these have shown 

 occasional mitotic figures. This is mentioned because the potentiality for 

 the formation of lutein-like tumor cells is present and these tumors will 

 probably appear spontaneously in rare cases. 



All the above variations of spontaneous granulosa-cell tumors are 

 probably benign. There are, however, mitotic figures in some cases, and 

 the tumor masses may be fairly large and nodular in outline. Some 

 sarcoma-like tumors have foci that suggest granulosa-cell tumors. These 

 are difficult to diagnose with certainty. 



Cavernous hemangioma is occasionally seen in the ovaries of mice. Still 

 more uncommon is hemangio-endothelioma which has been observed a few 

 times. True fibrosarcoma of the ovary is also rare in our stocks. A few of 

 these tumors have been diagnosed as primary at this site. Fibromas have 

 not been observed in our mice. 



Embryonal tumors of the ovary. — A rare, benign tumor of the ovary is 

 the teratoma. This usually shows a mixture of bone, cartilage, striated 

 muscle and gland structures as well as other tissues. There may be skin, 

 nerve or almost any tissue in this type of tumor (Fig. 123). 



Occasionally there is a tumor composed of closely packed epithelial cells 

 arranged as in embryonic gland formation. This is called an embryonal 

 adenoma and is benign. The cells are uniform, small and deeply staining. 

 Mitoses are rare. 



Embryonal cell carcinoma is composed of large, rounded, pale epithelial 

 cells varying in size. They have a fair amount of pale cytoplasm and 

 rounded, hypochromatic nuclei with coarse chromatin granules. These 

 cells are compactly arranged without much stroma; mitoses are abundant. 



Uterine Tumors 



Epithelial tumors at this site are rare in mice (58). Our records show 

 that adenomas have been observed twice in the dba stock. Carcinoma 

 simplex has also been observed in two mice, both hybrids, one from a cross 

 between dba and C57 black, the other from a cross of dba with yellow. The 

 former is shown in Figs. 124A and 125. Here the epithelium can be seen 



