Le follicule ovarien bovin au cours des différentes étapes de son développement : caractérisation in vivo et in vitro

Doctorat en sciences - UCL, 200

Characterization of in vitro growth of bovine preantral ovarian follicles : a preliminary study

International audienc

Characterization of in vitro growth of bovine preantral ovarian follicles : a preliminary study

International audienc

迴向自然的詩學

Thème: Folliculogenesis, oogenesis and superovulationAbstract + posterThe LH surge promotes prostaglandin E2 (PGE2) production within the preovulatory follicle. Oocytemicroenvironment levels of PGE2 affect the developmental competence after fertilization. This studyaimed to characterize the follicular fluid PGE2 enrichment during superovulation treatment. Six heifers(Holstein, 20.3 +/-0.85 months old) received FSH (Stimufol®, Reprobiol, Belgium): half dose, ie, 250 μgof porcine follitropin (pFSH), combined with 50 μg of porcine lutropin (pLH). At the rate of 8 injections,in degressive dose, spread over 4 days. PGF2α (Estrumate®, MSD Santé Animale, France) was injectedat the same time as the 5th injection of Stimufol®.LH peak was assumed to occur between 35 and 40hours after the PGF2α injection. Individual sampling of fluid from antral follicles was performed byovum pick up 12 hours before PGF2α injection and 60 hours after PGF2α injection. This protocol wasdesigned to allow the collection of fluids from ovarian follicle containing either a pre-matured or amatured oocyte. Each heifer was his own control as we took the "pre-matured" follicular fluid on a firstovary and the "matured" follicular fluid on the 2nd ovary, 3 days later. The punctures were repeatedtwice and were cross-checked for the next repetition to evaluate the impact of the ipsi or contralateralside of the corpus luteum (CL) on the follicular fluid composition. The volume of fluid was measured foreach punctured follicle. The PGE2 concentration of the follicular fluid was measured by Elisa (CaymanChemical) to determine the progress of terminal follicular differentiation. An average of 13 +/- 5.06 and28 +/-13.9 follicles were punctured per session/heifer for respectively pre-matured (n=78) and matured(n=169) follicles. The mean collected volume differed between the two groups (pre-matured: 0.229+/-0.213 ml/follicle; matured: 0.575+/-0.379 ml/follicle; two samples t-test, pval<0.0001). No effect of theside of CL on fluid volume was detected (2-way Anova, p=0.397). The PGE2 concentration wasdetermined in 25 pre-matured follicles and 127 matured follicles. The mean PGE2 concentrationsignificantly differed between the two groups of follicular fluids (pre-matured: 7.2 +/-7.5 ng/ml; matured:60.2 +/-58.6 ng/ml) No effect of the side of CL was detected (p=0.278). Surprisingly, there was no linearrelationship between fluid volume and PGE2 concentration (adjusted R-squared: -0.0002, pvalue=0.327). PGE2 concentrations were very spread out within the matured group. This importantdispersion (Interquartile range=58.6 ng/ml) indicated that despite follicle growth in response to hormonalstimulation (FSH/LH) the ability of follicular granulosa and cumulus cells to synthesize PGE2 wasimperfectly achieved. Only 48% of the follicular fluids in the mature group had higher PGE2 levels thanthose in the premature follicle group. In conclusion, despite the ability of the stimulation treatment topromote growth of many follicles, there was a great heterogeneity in terms of PGE2 synthesis. Thisalteration could represent defective signaling mechanisms that could impact the developmentalcompetence of the oocyte

Effect of roscovitine, a cdk1 inhibitor, and of the presence of oocyte on bovine cumulus cell expansion and cyclooxygenase-2 expression

International audienc

Cumulus cell cox-2 expression is a better predictor of oocyte developmental competence than gremlin expression in cattle

International audienc

Alteration of prostaglandin synthesis regulation in cumulus cells might affect the oocyte and embryo quality in dairy cows with unfavorable haplotype ''Fertil-'' of one female fertility quantitative trait locus located on chromosome 3

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Expression des Pregnancy associated glycoproteins par les cellules trophoblastiques et par les cellules du cumulus chez le bovin

National audienc

Analyse de la maturation ovocytaire et de l'expression génique dans les cellules du cumulus chez des vaches laitières portant les haplotypes Fertil+ et Fertil- d'un QTL de fertilité situé sur le chromosome 3

Our previous study featuring Fertil+ and Fertil- heifers, genotyped for one female fertility QTL located on chromosome 3 (QTL-F-Fert-BTA3), highlighted a difference in oocyte maturation in vivo and in in vitro embryo quality between the two haplotypes. Cumulus cells (CC), which enclose the oocyte, play an important role in the acquisition of female gamete competence to be fertilized and to undergo early embryo development by supporting the oocyte metabolism. Here, immature and mature cumulus oocyte complexes (COC) recovered by Ovum Pick Up were analyzed from cows in third lactation (8 Fertil+, 8 Fertil-). A meiotic maturation delay of the oocytes was observed after in vivo and in vitro maturation in Fertil- cows compared to Fertil+ ones. Three genes included in the QTL-Fert-F-BTA3 had similar expression in CC of in vivo matured oocytes. Nevertheless, significant differences in PTGS2 and PTGES1 prostaglandin synthase gene expression were detected in CC from Fertil- in vivo matured preovulatory COC. After IVM, the expression of one gene from the QTL, PEX19, one gene involved in oocyte quality, HAS2, as well as PTGES1 were shown to be decreased in Fertil- Cumulus Cells (CC). Taken together, these data suggest that differences in prostaglandin synthesis regulation of preovulatory follicles affect oocyte maturation and consequently fertility between these two haplotypes. New perspectives were introduced in order to understand molecular mechanisms related to early gestation failure in Fertil- cows.Notre précédente étude menée sur les génisses Fertil+ et Fertil- génotypées pour un QTL de fertilité femelle situé sur le chromosome 3 (QTL-Fert-F-BTA3) avait mis en évidence une différence de maturation ovocytaire in vivo ainsi qu’une différence de qualité embryonnaire in vitro entre ces deux haplotypes. Les cellules du cumulus (CC) qui entourent l’ovocyte jouent un rôle important dans l’acquisition de l’aptitude d’un gamète femelle à être fécondé et à soutenir le développement embryonnaire précoce en supportant le métabolisme ovocytaire. Ici, nous avons analysé les complexes ovocyte-cumulus (COC) immatures et matures de huit vaches Fertil+ et huit Fertil- en 3ème lactation collectés par Ovum Pick Up. Un arrêt précoce ou un retard de la maturation méiotique des ovocytes a été observé chez les Fertil- après maturation in vivo et in vitro comparés aux Fertil+. Nous n’avons observé aucune différence d’expression entre les deux haplotypes concernant 3 gènes du QTL-Fert-F-BTA3 dans les CC des ovocytes maturés in vivo. En revanche, des différences significatives d’expression de gènes des prostaglandines (PGE) synthases PTGS2 et PTGES1 ont été montrées entre les CC entourant les ovocytes maturés in vivo des vaches Fertil+ et Fertil-. Un gène du QTL, PEX19, ainsi qu’un gène lié à la qualité ovocytaire, HAS2 de même que PTGES1 sont moins exprimés dans les CC des Fertil- après maturation in vitro (MIV). Ces données suggèrent que les différences dans la régulation de synthèse des prostaglandines dans les follicules pré-ovulatoires altèrent la maturation ovocytaire et donc la fertilité entre ces deux haplotypes, et ouvrent de nouvelles perspectives pour comprendre les mécanismes moléculaires menant aux échecs précoces de la gestation chez les vaches Fertil-

Expression du système IGF et des récepteurs aux gonadotropines au sein du complexe ovocyte-cumulus bovin au cours de la maturation

National audienc