Features of follicle-stimulating hormone-stimulated follicles in a sheep model: keys to elucidate embryo failure in assisted reproductive technique cycles.
OBJECTIVE
To evaluate the individual functionality of gonadotropin-stimulated preovulatory follicles, for understanding embryo failure in assisted reproductive technique cycles, in a sheep model.


METHODS
Observational, model study.


METHODS
Public research unit.


METHODS
Fifteen adult Manchega ewes.


METHODS
Synchronization of the estrous cycle with intravaginal progestagens and ovarian stimulation with FSH; evaluation of reproductive activity, plasma sampling, ovarian ultrasonography, and ovariectomies.


METHODS
Determination of estrus behavior, plasma and intrafollicular concentrations of E(2) and inhibin A, number and size of ovarian follicles, and developmental competence of oocytes.


RESULTS
These results support the usefulness of serial measurements of plasma inhibin A for assessment of follicular growth during the FSH treatment, rather than of E(2) assays commonly used. Functionality of FSH-stimulated preovulatory follicles is clearly disturbed, as confirmed by a negative correlation between follicular size and intrafollicular concentrations of inhibin A and E(2) in preovulatory follicles after individual dissection; moreover, the ability of their oocytes to resume meiosis was diminished.


CONCLUSIONS
Functionality of follicles in controlled ovarian stimulation (COS), and developmental competence of their oocytes, is disturbed by the high doses of gonadotropin supplied and finally determined by follicular sizes at starting FSH treatment.
Veiga-Lopez
Almudena
A
Departamento de Reproduccion Animal, Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria, Madrid, Spain. aveiga@umich.edu
Dominguez
Veronica
V
Souza
Carlos J H
CJ
Garcia-Garcia
Rosa M
RM
Ariznavarreta
Carmen
C
Tresguerres
Jesus A F
JA
McNeilly
Alan S
AS
Gonzalez-Bulnes
Antonio
A
D000465:Algorithms; D000818:Animals; D002452:Cell Count; D048429:Cell Size; D002478:Cells, Cultured; D020964:Embryo Loss / Q000209:etiology*; D047108:Embryonic Development / Q000187:drug effects; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D023421:Models, Animal; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development; D011247:Pregnancy; D027724:Reproductive Techniques, Assisted / Q000009:adverse effects*; D012756:Sheep / Q000502:physiology*; D013480:Superovulation / Q000187:drug effects / Q000502:physiology
D004958:Estradiol; D005640:Follicle Stimulating Hormone