title: Temporal relationships of the LH surge and ovulation to echotexture and power Doppler signals of blood flow in the wall of the preovulatory follicle in heifers.
abstract: Changes in echotexture and blood flow in the wall of preovulatory follicles in heifers were studied in relation to the LH surge and ovulation in gonadotrophin-releasing hormone-induced (n = 7; Experiment 1) and spontaneous (n = 8; Experiment 2) ovulators. Ultrasonographic examinations and blood sampling were performed either every hour (Experiment 1) or every 6 h (Experiment 2). The interval from LH peak to ovulation in induced and spontaneous ovulators was 27.1 +/- 0.3 and 34.5 +/- 1.5 h, respectively. Follicle diameter did not increase between the LH peak and ovulation. In the induced ovulators, serration of the stratum granulosum was detected in one (14%), two (29%), three (43%) and four (57%) heifers at 4, 3, 2 and 1 h before ovulation, respectively. An initial increase in blood flow (P < 0.001) encompassed the LH peak in both experiments. In the induced ovulators, blood flow increased (P < 0.02) to maximum 3 h after the LH peak, maintained a plateau for 5 h, decreased (P < 0.05) between 9 and 14 h, increased (P < 0.05) again between 19 and 21 h and then decreased (P < 0.01) between 25 and 26 h (1 h before ovulation). The biphasic increase and decrease in blood flow and serration of the granulosum in the wall of the preovulatory follicle in cattle are novel findings.
authors.affiliation: Eutheria Foundation, Cross Plains, WI 53528, USA. masiddiqui@wisc.edu
authors.forename: M A R
authors.initials: MA
authors.lastname: Siddiqui
authors.forename: J C
authors.initials: JC
authors.lastname: Ferreira
authors.forename: E L
authors.initials: EL
authors.lastname: Gastal
authors.forename: M A
authors.initials: MA
authors.lastname: Beg
authors.forename: D A
authors.initials: DA
authors.lastname: Cooper
authors.forename: O J
authors.initials: OJ
authors.lastname: Ginther
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D007986:Luteinizing Hormone / Q000097:blood / Q000502:physiology*; D006080:Ovarian Follicle / Q000098:blood supply / Q000000981:diagnostic imaging / Q000502:physiology*; D010060:Ovulation / Q000502:physiology*; D013997:Time Factors; D018608:Ultrasonography, Doppler / Q000662:veterinary; D014741:Video Recording
chemical_list: D007986:Luteinizing Hormone