Bovine Model to Study Ovarian Function and Oocyte Competence in Women during Perimenopausal Period
Notice bibliographique
Résumé
The introduction of transrectal ultrasonography in late 1980's provided a unique non‐invasive tool to image ovarian structures over time. The technique allowed assessment of dynamics of follicle growth and regression in cows leading to validation of the wave theory of follicular growth. Over the past three decades, studies in the bovine model have focused on the characteristics of the dominant follicle selection, control of wave emergence, synchronization of ovulation, and the temporal relationship of oocyte's ability to develop into a blastocyst (oocyte competence) with the status of the dominant follicle. Studies of this nature are unethical and difficult to conduct in women. Follicular waves have been described in every monovular mammalian species in which ultrasonographic approach have been applied since the first description in cattle (in 1989) including humans (in 2003). Differences in selection of the dominant follicle and control of luteal function between humans and domestic animals appear to be more in detail rather than in essence. Relatively large diameters of the dominant follicles for clinical manipulations (e.g., follicle ablation for wave emergence, monitoring gonadotropin response during superovulation, ultrasound‐guided oocyte retrieval for in vitro fertilization), long life span of cows (15 to 20 years) and presence of multiple generations of animals on the same farm make cattle as one of the most suitable model to understand ovarian and oocyte function during perimenopausal period in women. Our research group have discovered that compared to young daughters (3–5 years), old cows (≥13 years) have elevated concentrations of FSH (similar to humans) and a marked decrease in embryo recovery documenting the effects of maternal age on oocyte competence. Maternal aging in cattle altered the timing of the preovulatory LH surge. Further, transcriptome analysis of granulosa cells from aged cows detected a suboptimal response to exogenous LH treatment indicating the possible mechanism by which the maternal age influences oocyte competence. In contrast to maternal aging, follicular aging (4‐day FSH followed by 96 hours of gonadotropin starvation) in younger cows led to reduced ovulation rates, accumulation of large lipid droplets in the oocyte, fertilization failures, and decreased blastocyst rate highlighting the multifaceted nature of factors that can influence oocyte competence. Interestingly, oocyte ability to develop into embryos was maintained if FSH support was continued. As a natural extension of our research, we have started to examine the influence of FSH superstimulation on oocyte competence during pre‐pubertal age in calves as young as 4‐month of age. Our working hypothesis is that the endocrine milieu and local ovarian factors responsible for low developmental competence of oocytes during the pre‐pubertal period are unique and distinct from those that cause the loss of competence during old age in the bovine model. Support or Funding Information Research supported by grants from the Natural Sciences and Engineering Council of Canada This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».