224 



BIOLOGY OF THE LABORATORY MOUSE 



Solid tumors. — In the non-tumorous ovary the changes of the follicular 

 cells into granulosa cells and their further differentiation to form lutein 

 cells are not sharp but gradual. For this reason definite lines cannot be 

 drawn, and borderline cell types can be observed. Therefore, there is 

 justification for considering that the tumors made up of cells resembling 

 the above phases should be grouped together. The growing tendency is to 

 call all such tumors granulosa-ccll tumors. This type is the most common of 



Fig. 122. — Papillary cyst adenoma of the ovary (X200). 



the solid ovarian tumors observed here. Grossly they are usually rather 

 large. 



This places in one group tumors that show a wide variation in the type 

 and arrangement of cells. The cells may be fairly uniform and rather 

 closely resemble foUicular, granulosa, theca or lutein cells. However, there 

 is often what appears to be a mixture of two or more of these cell types. 

 The cells may be arranged in a pattern that resembles closely packed, large 

 and small follicles, some distinct and some confluent, separated by thin 

 septa of stroma. Sometimes the cells grow in irregular cords which bear a 

 resemblance to the trabeculae seen in the early stages of corpus luteum 

 formation. There may also be seen more or less solid masses of cells with 

 some stroma and scattered, almost gland-like foci that resemble attempted 

 follicle formations. There are other tumors with large, pale, spindle shaped 



