lesions that were considered naturally occurring were surveyed in female sencar mice used in short - term bioassays . 
 these lesions were encountered in selected target organs and in organs and tissues with gross lesions encountered at necropsy . 
 the genitourinary system was the most frequent site for lesions ; cystic ovaries , cystic endometrial hyperplasia , and glomerulonephritis were commonly encountered in this system.imagesfigure 1.figure 2.figure 3.figure 4.figure 5.figure 6.figure 7.figure 8.figure 9.figure 10.figure 11.figure 12.figure 13.figure 14.figure 15.figure 16.figure 17 .