Development of one vs multiple ovulatory follicles and associated systemic hormone concentrations in mares.
Ablation of follicles > or = 6 mm in diameter and treatment with PGF2alpha 10 days after ovulation were used to induce the development of ovulatory waves. Comparisons were made between induced waves with one (33 waves, 72%) and multiple (13 waves, 28%) ovulatory follicles. Diameter deviation was defined as the separation of follicles into dominant and subordinate categories. Multiple ovulatory follicles were preceded by more (p < 0.001) follicles > or = 20 mm at the beginning of deviation, higher LH preceding deviation (approached significance, p < 0.08), lower (p < 0.05) concentrations of FSH on the day of deviation and thereafter, and higher (p < 0.0003) oestradiol by 2 days after deviation. During the peri-ovulatory period, systemic hormone concentrations for waves with multiple ovulations involved higher oestradiol before ovulation (approached significance, p < 0.07), lower FSH (p < 0.04) before and after ovulation, and both higher progesterone (p < 0.05) and lower LH (p < 0.05) beginning the day after ovulation. Results indicated that by the beginning of deviation there were more follicles > or = 20 mm and subsequently greater oestradiol production in waves that led to the development of multiple ovulatory follicles, and during the peri-ovulatory period differences between one and multiple ovulations were consistent with the negative effects of the ovarian hormones on the gonadotropins.
Ginther
O J
OJ
Eutheria Foundation, Cross Plains, WI 53528, USA. ginther@svm.vetmed.wisc.edu
Jacob
J C
JC
Gastal
M O
MO
Gastal
E L
EL
Beg
M A
MA
D000818:Animals; D015237:Dinoprost / Q000008:administration & dosage; D004958:Estradiol / Q000097:blood*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D006736:Horses / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood*; D006080:Ovarian Follicle / Q000033:anatomy & histology / Q000502:physiology* / Q000601:surgery; D010053:Ovary / Q000000981:diagnostic imaging; D010060:Ovulation / Q000502:physiology; D011374:Progesterone / Q000097:blood; D013396:Suction; D014463:Ultrasonography
D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D015237:Dinoprost