Relative mRNA abundance in granulosa cells of the two largest follicles in saline or FSH-treated cows. Cows were treated twice a day (12 h apart) with FSH (30, 30, 20 and 20 mg) or saline (control) starting on day 2 after ovulation. Granulosa cells were collected from the two largest follicles 12 h after the last administration of FSH (n = 4 pairs) or saline (n = 3 pairs). Abundance of ESR1 and ESR2 are expressed as mean ± SEM. * indicates statistical difference (P ≤0.05) between largest and second largest follicles.