title: Changes in concentrations of follicular fluid factors during follicle selection in mares.
abstract: The temporal relationships in the changes in concentrations of follicular fluid factors during follicle selection were characterized in mares. All follicles > or =5 mm were ablated 10 days after ovulation, followed by follicular fluid collection from the three largest follicles (F1, F2, and F3) when F1 of the new wave reached a diameter of 8.0-11.9, 12.0-15.9, 16.0-19.9, 20.0-23.9, 24.0-27.9, or 28.0-31.9 mm (n = 4-8 mares/range). Diameter deviation between F1 and F2 began during the 20.0- to 23.9-mm range, as indicated by a greater difference in diameter between the two follicles at the 24.0- to 27.9-mm range than at the 20.0- to 23.9-mm range. Androstenedione concentrations increased in F1, F2, and F3 between the 16.0- to 19.9- and 20.0- to 23.9-mm ranges. In contrast, estradiol, free insulin-like growth factor (IGF)-1, activin-A, and inhibin-A concentrations increased only in F1 beginning at the 16.0- to 19.9-mm range. As a result, the concentrations of all four factors were higher in F1 than in F2 and F3 at all the later ranges, including the 20.0- to 23.9-mm range (beginning of diameter deviation). Concentrations of progesterone differentially increased in F1, concentrations of androstenedione and IGF-binding protein (IGFBP)-2 increased only in F2 and F3, and concentrations of inhibin-B differentially decreased in F2 and F3 simultaneous with the beginning of deviation. Concentrations of FSH, LH, pro-alphaC inhibin, and total inhibin did not change differentially among follicles. Results indicated that, on a temporal basis, estradiol, free IGF-1, activin-A, and inhibin-A may have played a role in the initiation of follicle deviation. In addition, these four factors as well as progesterone, androstenedione, IGFBP-2, and inhibin-B may have been involved in the subsequent differential development of the follicles.
authors.affiliation: Department of Animal Health and Biomedical Sciences, University of Wisconsin, 1656 Linden Drive, Madison, WI 53706, USA. donadeu@ahabs.wisc.edu
authors.forename: F X
authors.initials: FX
authors.lastname: Donadeu
authors.forename: O J
authors.initials: OJ
authors.lastname: Ginther
mesh_terms: D028341:Activins / Q000032:analysis; D000735:Androstenedione / Q000032:analysis; D000818:Animals; D004958:Estradiol / Q000032:analysis; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry*; D006736:Horses / Q000502:physiology*; D028322:Inhibin-beta Subunits / Q000032:analysis; D007265:Inhibins / Q000032:analysis; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000032:analysis; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D006080:Ovarian Follicle / Q000033:anatomy & histology / Q000502:physiology*; D010060:Ovulation; D011374:Progesterone / Q000032:analysis
chemical_list: D018971:Insulin-Like Growth Factor Binding Protein 2; C422405:activin A; C422362:inhibin A; C422364:inhibin B; D028341:Activins; D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol; D007265:Inhibins; D007334:Insulin-Like Growth Factor I; D028322:Inhibin-beta Subunits