title: Effects of the persistent dominant follicle on the ability of follicle stimulating hormone to induce follicle development and ovulatory responses.
abstract: Three experiments were conducted to evaluate the effect of an induced first wave persistent dominant follicle on folliculogenesis and ovulatory responses induced by FSH. On d 6 of a synchronized estrous cycle (d 0 = estrus), cows were treated with a Syncromate-B implant and two injections of PGF2, (25 mg, 0700 h; 15 mg, 1900 h, i.m.). Cows in the control group retained a first-wave persistent dominant follicle, but in the aspirated group, the first-wave dominant follicle was removed via transvaginal aspiration on d 10 (d 0 = estrus). Beginning on d 12, cows received 32 mg of FSH-P i.m. in decreasing doses at 12-h intervals over a 4-d period. On d 15, the Syncromate-B implant was removed, and cows were ovariectomized (experiment 1, n = 8) or inseminated (experiment 2, n = 11) at 10 and 22 h after the onset of estrus. Cows in experiment 3 received a used controlled intravaginal drug releasing (CIDR) device and two injections of PGF2alpha (25 mg, 0700 h; 15 mg, 1900 h; i.m.) on d 6. On d 8, the first-wave dominant follicle was aspirated (n = 6) or left intact (n = 5), and FSH treatment was initiated (20 mg of Folltropin in decreasing doses at 12-h intervals over a 4-d period), and on d 10 the used CIDR device was removed from all cows. Ovarian follicle size and number were examined daily by ultrasonography from d 5 of the estrous cycle. The persistent dominant follicle increased in size from 10.7 mm on d 5 to 15.4 mm on d 10 (experiments 1 and 2), and from 9 mm on d 5 to 20.4 mm on d 11 (experiment 3). From d 11 to 14, the number of class 1 (2 to 5 mm) follicles was lower in the aspirated group than in the control group; the number of class 2 (6 to 9 mm) follicles was higher on d 12 and 13 for the aspirated group (experiments 1 and 2). The number of class 3 (> or =10 mm) follicles was higher in the aspirated group on d 14 to 16, but the same on d 17. Ovarian and embryo responses to superovulation did not differ between groups. In experiment 3, the numbers of class 1, 2, and 3 follicles, as well as ovarian and embryo responses following ovulation did not differ between groups. Initiation of exogenous FSH treatment appears to override any systemic inhibitory effect that a persistent dominant follicle may be exerting at the pituitary and possibly the ovary.
authors.affiliation: Department of Dairy and Poultry Sciences, and University of Florida, Gainesville 32611-0920, USA.
authors.forename: T
authors.initials: T
authors.lastname: Diaz
authors.forename: S M
authors.initials: SM
authors.lastname: Pancarci
authors.forename: M
authors.initials: M
authors.lastname: Drost
authors.forename: E J
authors.initials: EJ
authors.lastname: Schmitt
authors.forename: J D
authors.initials: JD
authors.lastname: Ambrose
authors.forename: W E
authors.initials: WE
authors.lastname: Fredriksson
authors.forename: W W
authors.initials: WW
authors.lastname: Thatcher
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D015237:Dinoprost / Q000494:pharmacology; D004338:Drug Combinations; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004971:Estrus; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood* / Q000494:pharmacology*; D007315:Insemination, Artificial; D006080:Ovarian Follicle / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure; D010052:Ovariectomy; D010060:Ovulation / Q000187:drug effects / Q000502:physiology; D010120:Oxytocics; D011282:Pregnenediones / Q000494:pharmacology; D013997:Time Factors; D014463:Ultrasonography; D014599:Uterus / Q000000981:diagnostic imaging
chemical_list: D004338:Drug Combinations; D010120:Oxytocics; D011282:Pregnenediones; C039187:Syncro-Mate B; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D015237:Dinoprost