Fig. 2.
Stages of the estrous cycle in UNC rats (A) and stages of the estrous cycle in rats exposed to BaP (B). Rats in the UNC group exhibited a normal 4-day estrous cycle characteristic of rodents (a= proestrus; b= estrus; c= diestrus I; d= diestrus II; approximately 24 hr /stage of the cycle). While the length of the cycle did not change for rats exposed to 50 and 75 μg BaP/m3, those exposed to 100 μg BaP/m3 sustained an increase in the duration of proestrus from approximately 24 to 48hr.