17ea-Hydroxylase and Aromatase Messenger Ribonucleic Acids in Cattle Undergoing Superovulation'

In this study, we tested the hypothesis that there is altered abundance of transcripts of genes coding for the enzymes cy-tochrome P450 17a-hydroxylase (P4501 7,,), cytochrome P450 aromatase (P450a,,), and 3-hydroxysteroid dehydrogenase (3-HSD) in follicles of cattle hyperstimulated with eCG com-pared to FSH. Treatments were initiated on Day 10 of the cycle, and all cows received prostaglandin (PG) on Day 12. In exper-iment 1, blood samples were taken to determine plasma pro-gesterone and estradiol concentrations during ovarian stimula-tion. In experiment 2, both ovaries were removed from stimu-lated cows by colpotomy before (n = 4 cows/treatment) and at 12 (n = 3/treatment) and 24 h (n = 3/treatment) after PG in-jection, and from nonstimulated controls (n = 4) 72 h after PG. The preovulatory follicle from nonstimulated heifers, and all fol