Manipulation of Follicular Development to Produce Developmentally Competent Bovine Oocytes1

Self Cite

One of the challenges in mammalian reproduction is to understand the basic physiology of oocyte quality. It is believed that the follicle status is linked to developmental competence of the enclosed oocyte. To explore the link between follicles and competence in cows, previous research at our laboratory has developed an ovarian stimulation protocol that increases and then decreases oocyte quality according to the timing of oocyte recovery post-FSH withdrawal (coasting). Using this protocol, we have obtained the granulosa cells associated with oocytes of different qualities at selected times of coasting. Transcriptome analysis was done with Embryogene microarray slides and validation was performed by real-time PCR. Results show that the major changes in gene expression occurred from 20 to 44 h of coasting, when oocyte quality increases. Secondly, among upregulated genes (20-44 h), 25% were extracellular molecules, highlighting potential granulosa signaling cascades. Principal component analysis identified two patterns: one resembling the competence profile and another associated with follicle growth and atresia. Additionally, three major functional changes were identified: i) the end of follicle growth (BMPR1B, IGF2, and RELN), involving interactions with the extracellular matrix (TFPI2); angiogenesis (NRP1), including early hypoxia, and potentially oxidative stress (GFPT2, TF, and VNN1) and ii) apoptosis (KCNJ8) followed by iii) inflammation (ANKRD1). This unique window of analysis indicates a progressive hypoxia during coasting mixed with an increase in apoptosis and inflammation. Potential signaling pathways leading to competence have been identified and will require downstream testing. This preliminary analysis supports the potential role of the follicular differentiation in oocyte quality both during competence increase and decrease phases.Reproduction (2013) 145 555-565

Section: Introductionsupporting

confidence: 51%

Section: Introductionmentioning

confidence: 75%

Changes in granulosa cells' gene expression associated with increased oocyte competence in bovine

Nivet¹,

Vigneault²,

Blondin³

et al. 2013

Self Cite

“…Gonadotrophins such as FSH either alone (Bousquet et al 1999, Goodhand et al 1999, Sirard et al 1999 or in combination with LH (Blondin et al 2002, see a review by Merton et al 2003) and pregnant mare serum gonadotrophin (Pieterse et al 1991) have been used to improve the outcome of OPU in adult donor cows. Oocytes from superovulated cows are developmentally more competent than their non-stimulated counterparts (Faber et al 2003, Merton et al 2003, and specific changes in superovulatory treatment can greatly increase developmental competence of the oocyte (Blondin et al 2002).…”

Section: Discussionmentioning

confidence: 99%

“…Oocytes from superovulated cows are developmentally more competent than their non-stimulated counterparts (Faber et al 2003, Merton et al 2003, and specific changes in superovulatory treatment can greatly increase developmental competence of the oocyte (Blondin et al 2002). However, due to high variability among gonadotrophin batches and being an animal product we considered ROH as a potential Table 6 Embryonic development of oocytes obtained during sessions 1 to 5 from cows treated with all-trans retinol (ROH) or corn oil (vehicle) and matured with or without 9-cis retinoic acid (RA).…”

Section: Discussionmentioning

confidence: 99%

Oocytes recovered from cows treated with retinol become unviable as blastocysts produced in vitro

Hidalgo¹,

Díez²,

Duque³

et al. 2005

Retinoids have been shown to enhance developmental competence of the oocyte in cattle, sheep and pigs. In this study we investigated whether exogenous retinol stimulates the bovine oocyte during its intrafollicular growth and the time limits of exposure to exogenous retinol. In addition, we also determined the efficiency of ovum pick-up techniques in combination with retinol treatment and the viability of embryos after transfer to recipients. In Experiment 1, heifers were injected with retinol or vehicle, and concentrations of retinol in the blood were analysed on Day 0 (prior to injection), Day 1 and, together with follicular fluid, Day 4. Blood retinol increased by Day 1 and cleared on Day 4, but retinol remained higher within the follicle. In Experiment 2, oocyte donors were injected weekly with retinol or vehicle four times during a twice-per-week cycle of eight recovery sessions (starting 4 days before the first session), followed by a second eight-session cycle without treatment. Oocytes recovered were fertilized and culturedin vitro.Retinol treatment yielded higher numbers of low-quality oocytes throughout, although retinol measured during cycles did not change. Total oocytes, and morulae and blastocyst rates, increased during the first five sessions following treatment with retinol. As previously shown with oocytes from slaughterhouse ovaries, retinoic acid stimulated blastocyst development. Following transfer to recipients, blastocysts from oocytes exposed to retinol were unable to establish pregnancy. Our study confirms the existence of an effect of retinol on the intrafollicular oocyte in the cow and provides evidence regarding the teratogenic effect of retinol.

“…However, developmental competence of oocytes is acquired through completion of both nuclear and cytoplasmic maturation. Only a small portion of in vitro-matured oocytes go on to develop into blastocysts, whereas oocytes matured in vivo have much higher embryo development rates (Van de Leemput et al 1999, Blondin et al 2002. Low blastocyst formation by in vitromatured oocytes indicates that current oocyte maturation systems do not adequately support either nuclear and/or cytoplasmic maturation.…”

Section: Introductionmentioning

confidence: 99%

Metabolic markers of developmental competence for in vitro-matured mouse oocytes

Preis¹,

Seidel²,

Gardner³

2005

In vitro maturation of oocytes has enormous potential in assisted reproductive technology, but its use has been limited due to insufficient knowledge of oocyte physiology during this dynamic period and lack of an adequate maturation system. The aim of this study was to characterize the metabolic profiles of three groups of oocytes throughout maturation: cumulus -oocyte complexes (COCs), denuded oocytes, and denuded oocytes co-cultured with cumulus cells. Mouse oocytes were collected from 28-day-old unstimulated females and matured in a defined medium. Oocytes were matured individually and transferred into fresh 0.5 ml drops of medium at 4 h intervals until 16 h. Ultramicrofluorimetry was used to quantitate carbohydrate consumption from and metabolite release into the medium. Glucose consumption and lactate production of COCs increased (P < 0.001) over the maturation interval (0 -16 h). Glucose consumption by COCs that subsequently fertilized was higher between 8-12 h of maturation than by COCs that did not fertilize (38 versus 29 pmol/COC per h, respectively; P < 0.01). Lactate production by COCs that subsequently fertilized was higher between 8-16 h of maturation, than by oocytes that did not fertilize (8 -12 h, 66 versus 46 pmol/COC per h, P < 0.01; 12-16 h, 56 versus 40 pmol/COC per h, respectively; P < 0.05). These data indicate that the final hours of maturation may hold a unique marker of oocyte competence, as during this time fertilizable COCs take up more glucose and produce more lactate than those not subsequently fertilized.