title: Oxytocin and estradiol concentrations in follicular fluid as a means for the classification of large bovine follicles.
abstract: Large antral follicles (13 to 20 mm in diameter) were collected from ovaries of 109 cows and 17 heifers that also had a regressed corpus luteum at slaughter. Thirty percent of the animals had been injected once with prostaglandin F(2)alpha 48 hours before slaughter. Follicles were divided into 3 groups based on estradiol and oxytocin concentrations in the follicular fluid: Group I follicles, estradiol>/=100 ng/ml and oxytocin<65 pg/ml (preovulatory and assumed pre-gonadotropin surge); Group II follicles, estradiol<100 ng/ml and oxytocin>/=65 pg/ml (preovulatory and assumed post-gonadotropin surge); and Group III follicles, estradiol<100 ng/ml and oxytocin<65 pg/ml (atretic follicles). Treatment with prostaglandin F(2)alpha significantly increased the number of viable granulosa cells and estradiol content in Group I follicles. The estradiol: progesterone ratio was significantly higher in Group I vs Groups II and III, but it was similar for Group II healthy follicles and Group III atretic follicles. To ascertain the classification of follicles, PGF(2)alpha was administered on Day 6 of the cycle to induce corpus luteum regression, and a GnRH analog was administered 24 hours later. At 23 hours after GnRH analog treatment, follicular oxytocin levels significantly rose to 103 pg/ml. Concomitantly, estradiol concentrations fell to below 100 ng/ml. This response was not evident by 13 h after injection of the GnRH analog. The results indicate that follicular estradiol and oxytocin concentrations may be used as a means for the physiological classification of large bovine follicles.
authors.affiliation: Department of Animal Science, Faculty of Agriculture The Hebrew University of Jerusalem, Rehovot 76100 Israel.
authors.forename: R
authors.initials: R
authors.lastname: Meidan
authors.forename: D
authors.initials: D
authors.lastname: Wolfenson
authors.forename: W W
authors.initials: WW
authors.lastname: Thatcher
authors.forename: E
authors.initials: E
authors.lastname: Gilad
authors.forename: L
authors.initials: L
authors.lastname: Aflalo
authors.forename: Y
authors.initials: Y
authors.lastname: Greber
authors.forename: E
authors.initials: E
authors.lastname: Shoshani
authors.forename: E
authors.initials: E
authors.lastname: Girsh