title: Follicular activity and hormonal secretory profile in vicuna (Vicugna vicugna).
abstract: The objective of the present study was to characterize ovarian activity in non-mated vicunas, relating ovarian structures (evaluated by transrectal ultrasonography, daily for 30 days) to changes in plasma concentrations of estradiol-17beta and progesterone. Ovarian follicular activity occurred in waves, characterized by the follicle emergence, growth and regression. The mean duration of follicular waves was 7.2+/-0.5 days (mean+/-S.E.M.), with a range of 4-11 days. The follicular growth phase averaged 3.0+/-0.2 days, the static phase 1.4+/-0.1, the regression phase 2.9+/-0.3 days, and the inter-wave interval was 4.2+/-0.3 days. The mean growth rate during the growing phase was 1.8+/-0.1mm/day, while the duration of the interval from 6mm to maximum diameter was 1.4+/-0.1 days. The mean maximum diameter of the dominant follicle was 8.4+/-0.3mm (range: 6.2-11.2) and mean diameter of the largest subordinate follicle was 5.4+/-0.1mm. There was an inverse relationship between the size of the largest follicle and the total number of follicles (r=-0.21, P=0.002). Follicle activity alternated between ovaries in 77% of the waves, with 40% of dominant follicles present in the left ovary and 60% in the right ovary. Plasma estradiol-17beta concentrations also had a wave-like pattern, varying between 12.0 and 62.8 pmol/l. Plasma progesterone concentrations remained below 5.0 nmol/l and there was no ultrasonographic evidence of ovulation during the study.
authors.affiliation: Area de Teriogenologi;a, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Chorroarin 280, Capital Federal 1427, Buenos Aires, Argentina. mmirag@fvet.uba.ar
authors.forename: M H
authors.initials: MH
authors.lastname: Miragaya
authors.forename: M A
authors.initials: MA
authors.lastname: Aba
authors.forename: E F
authors.initials: EF
authors.lastname: Capdevielle
authors.forename: M S
authors.initials: MS
authors.lastname: Ferrer
authors.forename: M G
authors.initials: MG
authors.lastname: Chaves
authors.forename: B
authors.initials: B
authors.lastname: Rutter
authors.forename: A
authors.initials: A
authors.lastname: Agüero
mesh_terms: D000818:Animals; D002161:Camelids, New World / Q000502:physiology*; D004958:Estradiol / Q000097:blood*; D005260:Female; D006080:Ovarian Follicle / Q000502:physiology*; D010053:Ovary / Q000000981:diagnostic imaging / Q000502:physiology; D011374:Progesterone / Q000097:blood*; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D011374:Progesterone; D004958:Estradiol