(A) Multiple exposure experimental timeline and cervicovaginal tissue exposure controls. Female Swiss Webster mice were exposed to N-9 daily for four days, resulting in four experimental groups of mice. Within each exposure group, subsets of mice were sacrificed at 10 min, 2 h, 4 h, or 8 h after exposure. (B-E) One mouse was exposed to saline and sacrificed after each post-exposure period. Photo micrographs (40× magnification) of representative tissues from the 2 h time point are shown. Vaginal (B, D) and cervical (C, E) epithelial tissues were examined for damage after a single exposure (B, C) or after 4 exposures (D, E) to saline. The tissue damage score (see also Table1) is shown in the lower right corner of each panel.