A) An estrogen challenge induced significant ovarian development in control+EE females as measured by the increased number of primary, secondary and antral follicles. In contrast, the estrogen challenge had no effect on ovarian development in BPS+EE females. B) Total numbers of follicles counted throughout the entire ovary were significantly increased in control+EE females but unaffected in BPS+EE females. C) Similar patterns were observed when measures of ovarian development were limited to only four sections for specific types of follicles and D) total follicles in four sections of ovary. In all panels, * indicates p<0.05, independent samples t-test comparing EE-challenged with non-challenged females from the same perinatal treatment group (control or BPS). δ indicates significant differences, p<0.05, between EE-challenged controls and EE-challenged BPS-treated females. In all groups, n=5 per treatment.