III. RESULTS: MICE 



Ovary: Ovarian abscesses were observed in 

 18/50 control female mice but in none of the 

 dosed mice (Table 24). Atrophy, characterized 

 by the absence of graafian follicles and corpora 

 lutea, occurred in 48/50 low dose and 49/50 high 

 dose female mice but not in controls. Uncommon 

 ovarian tumors including tubular adenomas, be- 

 nign mixed tumors, and granulosa cell tumors 

 occurred only in dosed female mice (Table 25). 

 Tubulostromal tumors form a continuous mor- 

 phologic spectrum and typically consist of com- 

 plex branching tubules originating from the 

 surface mesothelium and varying numbers of in- 

 tertubular cells derived from the ovarian stro- 

 ma. Those tumors with a minimum of stromal 



cells were classified as tubular adenomas, 

 whereas those with a prominent stromal cell 

 component were classified as benign mixed tu- 

 mors (Figures 13 and 14). The granulosa cell tu- 

 mors were characterized by the predominant 

 component of typical granulosa cells arranged in 

 a variety of patterns. The tumor diagnosed as a 

 neoplasm, NOS, is an extremely uncommon tu- 

 mor in B6C3Fi mice. The pattern of growth and 

 cellular morphology were characteristic of the 

 Sertoli cell tumor that occurs in the testis. Al- 

 though of unusual morphologic pattern, this tu- 

 mor is of sex cord origin similar to that of the 

 granulosa cell tumors. 



TABLE 24. 



NUMBER OF FEMALE MICE WITH OVARIAN LESIONS IN THE TWO-YEAR FEED STUDY 



OF NITROFURANTOIN 



Lesion 



Control 



1.300 ppm 



2,500 ppm 



Number examined microscopically 



Abscess 

 Atrophy 



Tubular adenoma 

 Cystadenoma 

 Papillary cystadenoma 

 Granulosa cell tumor, benign 

 Granulosa cell tumor, malignant 

 Mixed tumor, benign 

 Neoplasm, NOS 



50 



50 





 48 

 

 

 1 

 3 

 

 

 



50 





 49 

 5 

 1 

 

 1 

 1 

 4 

 1 



Nitrofurantoin, NTP TR 341 



56 



