Relationships between ultrasonographic and histophysiological attributes of individual ovarian structures in sheep and cattle

We used computer-assisted image analysis to objectively quantify and compare the ultrasonographic attributes of ovarian antral follicles in vivo, in cyclic and seasonally anestrous ewes, after various ovulation induction regimens (medroxyprogesterone acetate/equine chorionic gonadotropin, gonadotropin releasing hormone and prostaglandin F2alpha). The relationships were also examined between ultrasonographic characteristics and histophysiologial attributes of individual bovine antral follicles and corpora lutea (CL) ex situ. The present results have revealed that, in sheep, large antral follicles with different growth characteristics, ovulatory responses or luteal outcomes after hormonal treatments, have distinctive echotextural properties of the follicular antrum and wall, and that the echotextural variables are correlated with the histomorphological characteristics and rate of cell proliferation of bovine antral follicles. Therefore, our results present novel opportunities for validating computer-assisted analysis of ultrasonographic ovarian images as a robust, non-invasive technique for determining the developmental competence of antral follicles in vivo and histophysiological characteristics of the follicles ex situ.