Confirmation of estrus phases in the normal ovaries and morphology of cystic ovaries. Representative images were displayed for the follicular phase (A) developing follicles with luteolysis, luteal phase (B) with small follicle waves with mature corpus luteum, and cystic ovary with non-ovulatory, abnormally enlarged (> 1.5 cm), and fluid-filled follicle. While the follicular phase exhibited significantly (p < 0.01) higher estradiol and lower progesterone level, the luteal phase presented the opposite results.