247 THE IMPORTANCE OF FOLLICULAR DIFFERENTIATION TO OBTAIN FULLY COMPETENT BOVINE OOCYTES
Notice bibliographique
Résumé
Making an oocyte with the capacity to form a Day-7 embryo that will implant and produce a live healthy calf is a long and complex process. Since the beginning of bovine IVF, it has been clear that the follicle from which an oocyte is obtained is the most important factor to predict outcome. The blastocyst rate is above 75% with in vivo-matured oocytes, but success varies greatly following in vitro maturation, depending more on follicular status than size. Indeed, aspirating oocytes from non-preovulatory follicles can result in 30% blastocyst development following fertilization but rarely more, unless the follicle is selected. Follicles leading to improved development are either early atretic or exposed to FSH withdrawal. If no exogenous FSH is given, natural early atresia will occur the day after the dominant follicle is selected, but will be limited to a few follicles per wave. If FSH is given to generate a wave of dominant follicles, and then withdrawn, most of the follicles will continue growth and differentiation under basal LH and a maximal oocyte quality will be reached between Day 2 and 3 after the last FSH injection. Under these conditions, the oocyte has the right cascade of signaling to condense its chromatin and to prepare for fertilization. Oocytes obtained from less-prepared follicles are of lower quality, as demonstrated by lower blastocyst rates, lower blastocyst quality, lower implantation rates, and higher abortion rates. Genomic analysis of embryos generated from slaughterhouse-derived oocytes indicates a progressive dysfunction in direct link with the in vitro exposure time. The best way to minimize in vitro-related stress is to begin with a competent oocyte and the best demonstration of that is when some animals (treated with FSH and then coasted) generate 100% blastocyst rate for a recovery of more than 5 oocytes, indicating that the initial quality of oocytes is not much affected by the in vitro culture. It is surprising that blastocyst rates following coasting and in vitro maturation can surpass that observed with Day-7 embryo collections based on the number of ovulations. Finally, new epigenetic analysis will progressively unravel differences of oocytes obtained from different sources and will become an important research tool to assess follicular conditions that will lead to minimal culture stress and optimal embryo quality. If epigenetic programming of the embryo depends on its capacity to deal with the stress created by culture, as has been shown in other species, the initial quality of the oocyte will potentially impact the health status of the newborn calf and resulting adult.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,002 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
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 tête enseignante, 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 ».