title: Differences between follicular waves 1 and 2 in patterns of emergence of 2-mm follicles, associated FSH surges, and ovarian vascular perfusion in heifers.
abstract: The emergence (first detection) of 2-mm follicles, FSH surges, and ovarian vascular perfusion for follicular wave 1 and surge 1 (n = 26) and wave 2 and surge 2 (n = 25) were studied daily in heifers. The day the future dominant follicle was closest to 5.5 mm was designated Day 0 for each wave. In wave 1, many 2-mm follicles (41%) emerged on Days -5 to -3, whereas FSH surge 1 did not begin until Day -3. Concentration of FSH increased abruptly in 1 day to a peak on the day of maximal number of emerging 2-mm follicles, although the day of maximal number relative to Day 0 differed among individuals. The first emergence of 2-mm follicles in wave 2 occurred concurrently with the first increase in the FSH of surge 2. In wave 1, ovarian resistance to vascular perfusion was negatively correlated (r = -0.48, P < 0.05) with a number of 2-mm follicles on Days -4 to -1 for ovaries that did not contain the preovulatory follicle; vascular perfusion increased with an increase in the number of small follicles. The following hypotheses were supported for wave 1 but not for wave 2: (1) an increase in the number of emerging 2-mm follicles of a follicular wave occurs before the beginning of an increase in FSH, (2) the day of maximal number of emerging 2-mm follicles occurs concurrently with an abrupt FSH increase on different days among individuals, and (3) the association between the number of emerging 2-mm follicles and the extent of ovarian vascular perfusion is positive.
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA. Electronic address: ginther@vetmed.wisc.edu.
authors.forename: O J
authors.initials: OJ
authors.lastname: Ginther
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: M A R
authors.initials: MA
authors.lastname: Siddiqui
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Baldrighi
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Wolf
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Greene
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000000981:diagnostic imaging; D030762:Estrous Cycle / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D006080:Ovarian Follicle / Q000098:blood supply / Q000000981:diagnostic imaging / Q000254:growth & development*; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D005640:Follicle Stimulating Hormone
keywords: FSH; Follicle emergence; Follicular wave; Ovarian vascular perfusion; Small antral follicle