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Dynamics of follicle populations and gonadotropin concentrations in fillies age two to ten months
Author(s) -
NOGUEIRA G. P.,
GINTHER O. J.
Publication year - 2000
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.2746/042516400777584686
Subject(s) - dynamics (music) , follicle , gonadotropin , physiology , follicle stimulating hormone , biology , andrology , medicine , endocrinology , hormone , luteinizing hormone , physics , acoustics
Summary Follicle populations and concentrations of circulating gonadotropins were studied during age 2–10 months in 10 spring‐born pony fillies. Blood sampling and ultrasound scanning were done every 4 days and daily for four 30 day periods. During 5–12 weeks, FSH concentrations were lower in 6 fillies with follicles ≥ 6 mm (mean ± s.e. 1.4 ± 0.1 ng/ml) than in 4 fillies with follicles <6 mm (2.8 ± 0.3 ng/ml). The diameters and numbers of follicles and gonadotropin concentrations increased progressively during age 2–4 months. A plateau in follicle activity and reduced levels of gonadotropins occurred during 5–7 months. During 8–10 months, follicles grew to >10 mm and gonadotropin concentrations increased. Waves of follicular growth were identified during the 30 day periods by significant increases in the diameter of the 10 largest follicles. The waves did not partition into dominant and subordinate follicles. Results indicated an initial postnatal period of negative ovarian feedback, temporally related changes in gonadotropins and follicles for months 3–10, and development of follicles in waves.