Characteristics of Prolonged Dominant Versus Control Follicles: Follicle Cell Numbers, Steroidogenic Capabilities, and Messenger Ribonucleic Acid for

Cattle with low (subluteal) levels of plasma progesterone de-velop a persistent dominant follicle; plasma estradiol and LH pulse frequency are elevated, and fertility subsequent to the ovulation of a prolonged dominant follicle is compromised. The hypotheses were 1) that prolonged dominant follicles produce more estradiol because they have theca and granulosa cells with an enhanced capacity to produce androgen and estradiol, re-spectively, and 2) that these changes in steroidogenic capacity are paralleled by concomitant changes in mRNA for the appro-priate steroidogenic enzymes. Prolonged dominant follicles were induced by treating Holstein heifers with exogenous pro-gesterone via an intravaginal controlled internal drug-release de-vice (CIDR) from Day 14 to 28 of the cycle. Prolonged dominant follicles were collected just before (CIDRb, Day 28; n = 4) o