title: Systemic effect of follicle-stimulating hormone and intraovarian effect of the corpus luteum on complete regression vs recovery of regressing wave-2 follicles in heifers.
abstract: Each subordinate of the second follicular wave (wave 2) was monitored, and the outcome was classified as fully regressed (decreased in diameter to 2 mm) or recovered (decreased initially and then increased to become a growing follicle of the subsequent wave 1). The changing diameter of each follicle after emergence at 2 mm and plasma concentration of follicle-stimulating hormone were determined every 12 h from the day of ovulation (Day 0) to 4 d after the subsequent ovulation in heifers with 2 follicular waves per interovulatory interval (n = 10). The number and percentage of wave-2 subordinates that initially regressed and then recovered (7.2 ± 1.0 follicles; 33.2 ± 5.1%) were less (P < 0.0008) than the number and percentage that completely regressed (15.0 ± 1.7; 66.8 ± 5.1%). Follicles that later recovered initially reached maximal diameter on a later day (P < 0.0001) after emergence at 2 mm (4.3 ± 0.2 d) and at a larger (P < 0.0001) diameter (5.8 ± 0.2 mm) than follicles that completely regressed (3.2 ± 0.1 d; 4.7 ± 0.1 mm). The follicle-stimulating hormone surge that stimulated wave 2 began earlier and was more sustained in a subgroup with a high percentage of recovered follicles (61%) than in a subgroup with a low percentage (24%). Recovery began on Day -1.0 ± 0.1 when the follicles had regressed to 3.7 ± 0.1 mm. Diameter of subordinate follicles on Day -6 or before the expected days of luteolysis was greater (P < 0.05) when in the corpus luteum (CL) ovary than when in the non-CL ovary. During expected luteolysis, more follicles (P < 0.008) per ovary continued to regress when ipsilateral to the CL (9.2 ± 1.1 follicles) than when contralateral (5.8 ± 1.1), and more follicles (P < 0.02) recovered from regression when contralateral to the CL (5.0 ± 0.8) than when ipsilateral (2.2 ± 0.6). The hypothesis that the CL has a local effect on the development, regression, and recovery of the subordinate follicles of wave 2 was supported.
authors.affiliation: Eutheria Foundation, Cross Plains, WI, 53528, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 1656 Linden Dr, Madison, WI, 53706, USA. Electronic address: ginther@vetmed.wisc.edu.
authors.forename: O J
authors.initials: OJ
authors.lastname: Ginther
authors.affiliation: Eutheria Foundation, Cross Plains, WI, 53528, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 1656 Linden Dr, Madison, WI, 53706, USA.
authors.forename: M A R
authors.initials: MA
authors.lastname: Siddiqui
authors.affiliation: Eutheria Foundation, Cross Plains, WI, 53528, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 1656 Linden Dr, Madison, WI, 53706, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Baldrighi
authors.affiliation: Eutheria Foundation, Cross Plains, WI, 53528, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 1656 Linden Dr, Madison, WI, 53706, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Wolf
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D010060:Ovulation / Q000502:physiology*; D013997:Time Factors
chemical_list: D005640:Follicle Stimulating Hormone
keywords: FSH; Follicle persistence; Follicle recovery; Intraovarian effect; Subordinate