Patterns of expression of steroidogenic enzymes during the first wave of the ovine estrous cycle as compared to the preovulatory follicle

Abstract The expression patterns of steroidogenic enzymes in ovarian antral follicles at various stages of growth in a follicular wave have not been reported for sheep. Ovaries were collected from ewes ( n  = 4–5 per group) when the largest follicle(s) of the first wave of the cycle, as determined by ultrasonography, reached (i) 3 mm, (ii) 4 mm, (iii) ≥5 mm in diameter or when there was a single (iv) preovulatory follicle in the last wave of the cycle, 12 h after estrus detection. The expression pattern of steroidogenic enzymes was quantified using immunohistochemistry and grey-scale densitometry. The expression of CYP19 in the granulosa and 3β-HSD and CYP17 in the theca increased ( P P P P r  = 0.5; P