Neonatal exposure to bisphenol A or diethylstilbestrol alters the ovarian follicular dynamics in the lamb

We hypothesized that neonatal xenoestrogen exposure affects the ovarian follicular dynamics in lambs. Female lambs were exposed from postnatal day (PND) 1–14 to low doses of diethylstilbestrol (DES) or bisphenol A (BPA). At PND 30, the follicular dynamics and ovarian biomarkers (ERα, ERβ, AR, Ki67, p27) were evaluated. Lambs exposed to DES or BPA showed a decline in the stock of primordial follicles with stimulation of follicular development. BPA reduced ovarian weight and increased the number of multioocyte follicles. BPA promoted proliferation of granulosa/theca cells in antral follicles, and increased both the number of antral atretic follicles and p27 expression. Neonatal exposure to BPA or DES reduced the primordial follicle pool by stimulating their initial recruitment and subsequent follicle development until antral stage. In prepubertal lambs, the accelerated folliculogenesis resulted in increased incidence of atretic follicles. These alterations may affect the ovarian function in the adult.

• Lambs neonatally exposed to low doses of BPA or DES showed an altered follicular dynamics.
• BPA or DES promoted a decline in the stock of primordial follicles due to stimulation of follicular development, associated with increased granulosa/theca cell proliferation and follicular atresia.
• We used a precocious animal model that exhibits a follicular development similar to human.