The dominant follicle: the final frontier in oocyte development
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PROVIDER: PRJNA1266745 | ENA |
REPOSITORIES: ENA
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Project description:The acquisition of oocyte competence, involving both cytoplasmic and nuclear maturation, is critical for successful fertilization and embryonic development in mammals. Discrepancies between in vivo and in vitro studies underline the potential impact of assisted reproductive technologies (ARTs), such as FSH stimulation and in vitro maturation, on oocyte quality and the molecular integrity of bovine oocytes. These insights underscore the importance of optimizing ART conditions to enhance reproductive success in cattle production. Therefore, this study focuses on the gene expression and DNA methylation dynamics in bovine oocytes from dominant follicles, utilising single-cell bisulfite conversion and RNA sequencing (scG&T), without ovarian stimulation. Samples were collected from synchronized heifers during three time points from 24hr to 2hr before ovulation and submitted to scG&T and compared with a dataset of >120 um in diameter oocytes collected by ovary slicing. Our findings from the single-cell RNA sequencing highlight significant changes in oxidative phosphorylation transcripts, indicating the importance of energy metabolism during oocyte capacitation. Additionally, small changes in global CpG methylation and methylation over genomic features were observed. However, modest modifications in CpG windows suggest a less stable epigenome than previously assumed in fully-grown oocytes. In conclusion, the present study brings new insights into molecular changes in bovine oocytes collected from dominant follicles, which can contribute to oocyte quality improvement in cattle production.
2025-07-14 | GSE297927 | GEO
Project description:The objective was to determine age-associated changes in the transcriptome of granulosa cells recovered from the dominant follicle at the time of selection. Granulosa cells were collected from the dominant follicle of aged and young cows after ovariectomy (15 ±1.5 years, n=3 and 6 ± 1.1 years, n=3), or ultrasound-guided follicle aspiration (16±2.1 years, n=4 and 7±1.2 years, 6 ± 1.1 years, n=4) 3-days after ovulation (Day 0). Messenger-RNA was extracted, amplified, labeled with florescent dyes, and hybridized with bovine-specific microarrays (GEO accession # GPL13226). Target intensities were analyzed to determine differential gene expression in granulosa cells from aged vs. young cows. A total 169 genes were differentially expressed (⥠2 fold-change; Pâ¤0.05) between age groups. In conclusion, granulosa cells collected at the time of selection of the dominant follicle exhibited age-related changes in the transcriptome that may explain follicle-associated loss of oocyte competence in aged cows. Granulosa cells of the dominant follicle at the time of selection (aged vs.young cows). Three biological replicates (each composed of one aged and one young cow). 3 Three technical replicate (dye swap). One biological or technical replicate per array.
2016-03-31 | E-GEOD-52480 | biostudies-arrayexpress
Project description:The objective was to determine age-associated changes in the transcriptome of granulosa cells recovered from the dominant follicle at the time of selection. Granulosa cells were collected from the dominant follicle of aged and young cows after ovariectomy (15 ±1.5 years, n=3 and 6 ± 1.1 years, n=3), or ultrasound-guided follicle aspiration (16±2.1 years, n=4 and 7±1.2 years, 6 ± 1.1 years, n=4) 3-days after ovulation (Day 0). Messenger-RNA was extracted, amplified, labeled with florescent dyes, and hybridized with bovine-specific microarrays (GEO accession # GPL13226). Target intensities were analyzed to determine differential gene expression in granulosa cells from aged vs. young cows. A total 169 genes were differentially expressed (≥ 2 fold-change; P≤0.05) between age groups. In conclusion, granulosa cells collected at the time of selection of the dominant follicle exhibited age-related changes in the transcriptome that may explain follicle-associated loss of oocyte competence in aged cows.
2016-03-31 | GSE52480 | GEO
Project description:Vitrification is increasingly used to cryopreserve gametes and embryos in assisted reproductive technology (ART). Our prior research demonstrates that vitrification preserves the viability and functionality of ovarian follicles. However, its impact on follicle-enclosed oocyte remains unknown. The current study investigates whether vitrification, combined with a 3D encapsulated in vitro follicle growth (eIVFG) system, maintains oocyte transcriptome during in vitro follicle development and oocyte maturation. Immature mouse preantral follicles were vitrified and cultured in eIVFG for 8 days to grow to the preovulatory stage, followed with the induction of ovulation and oocyte maturation on day 9, with fresh follicles as the control. Oocytes at germinal vesicle (GV) stage from grown preovulatory follicles on day 8 and oocytes at metaphase II (MII) upon ovulation on day 9 were collected for single-oocyte Smart-Seq2 RNA sequencing analysis. The principal component analysis (PCA) separated GV and MII oocytes into two distinct clusters, but oocytes from fresh and vitrified follicles were largely overlapped. Differential gene expression (DEG) analysis revealed that GV or MII oocytes from fresh and vitrified follicles had comparable expression of maternal effect genes and other genes related to oocyte meiotic and developmental competence. There was a significant transcriptomic change during the GV-to-MII transition. Gene ontology (GO) and KEGG analysis identified DEGs between GV and MII oocytes related to cell cycle, RNA processing, mitochondria, and ribosome. In summary, our study demonstrates that vitrification preserves oocyte transcriptome during in vitro follicle development and oocyte maturation, supporting its potential in fertility preservation. Moreover, our single-oocyte RNA sequencing analysis identifies key DEGs upon GV-to-MII transition, indicating their potential functions in underpinning oocyte meiotic and developmental competence.
2025-04-02 | GSE292062 | GEO
Project description:oocytes were collected from ovarys of 6 day old female mice. Targets from four biological replicates of each were generated and the expression profiles were determined using Affymetrix MOE430 A & B. Experiment Overall Design: 4 oocyte at primary follicle stage biological replicates were analyzed
2008-06-12 | E-GEOD-3291 | biostudies-arrayexpress
Project description:Differences in follicle-stimulating hormone (FSH) ß-subunit N-glycosylation results in distinct FSH glycoforms. Hypoglycosylated FSH21 is more bioactive and abundant in reproductively young women, whereas fully glycosylated FSH24 shows lower bioactivity and a relative increase with age. To investigate if the coinciding shift in FSH glycoform abundance contributes to the age-dependent decline in oocyte quality, an encapsulated in vitro follicle growth system was utilized to examine the direct effects of FSH glycoforms on folliculogenesis and resulting oocyte quality. Long-term culture (10-12 days) with FSH21 (10 ng/ml) enhanced follicle growth, estradiol secretion, and oocyte quality compared to equivalent FSH24 treatment. FSH21 exhibited enhanced capacity to establish transzonal projections, gap junctions, and cell-to-cell communication within 24 hrs in culture. Transient inhibition of FSH21-mediated bidirectional communication abrogated the positive effects of FSH21 on follicle growth, estradiol secretion and oocyte quality. These findings indicate FSH21 promotes folliculogenesis and oocyte quality in vitro through increasing cell-to-cell communication early in folliculogenesis and that the shift in abundance from FSH21 to FSH24 with reproductive aging could contribute to the age-dependent decline in oocyte quality.
2023-07-15 | GSE236967 | GEO
Project description:The objective of the study was to compare the transcriptome of the bovine oocyte coming from distinct follicle sizes.
2015-11-15 | GSE48283 | GEO
Project description:The Objective of this study was to establish global gene expression profiles associated with different stages of dominant follicle development in the horse. This was done by collecting ovaries at different stages of an ovulatory follicular wave, when the dominant follicle reached 22 mm (early dominant, ED), 33 mm (late dominant, LD) and 34 h after an i.v. injection of crude equine gonadotropins (CEG; 15 mg i.v.) when the largest follicle reached > 33 mm (preovulatory stage, PO). RNA was then separately collected from granulosa cells and theca-rich follicular wall fractions and was hybridized to the Agilent Horse Gene Expression Microarray. Gene expression was compared between ED and LD and between LD and PO stages within each of granulosa cells and theca walls. Significantly larger numbers of genes were differentially expressed in granulosa cells than in theca walls throughout development, and between LD and PO follicles than between ED and LF follicles. The most salient features were the downregulation of cell cycle genes in granulosa cells during both the ED-LD and LD-PO transitions and the upregulation of genes associated with inflammation, immunity, extracellular matrix remodelling and protection aganints toxic insult in both GCs and TCs, particularly during the LD-PO transition. Five to nine biological replicates per cell type and developmental stage (total of 34 samples) were used in a single dye experiment. Samples were distributed among slides so that each experimental groupeach was represented at least once in each slide. For each gene, mean normalized intensities (n= 5 biological replicates/group) were compared between follicle stages (ED-LD and LD-PO) within each cell type (GC and TC).
2014-03-15 | E-GEOD-52109 | biostudies-arrayexpress
Project description:The Objective of this study was to establish global gene expression profiles associated with different stages of dominant follicle development in the horse. This was done by collecting ovaries at different stages of an ovulatory follicular wave, when the dominant follicle reached 22 mm (early dominant, ED), 33 mm (late dominant, LD) and 34 h after an i.v. injection of crude equine gonadotropins (CEG; 15 mg i.v.) when the largest follicle reached > 33 mm (preovulatory stage, PO). RNA was then separately collected from granulosa cells and theca-rich follicular wall fractions and was hybridized to the Agilent Horse Gene Expression Microarray. Gene expression was compared between ED and LD and between LD and PO stages within each of granulosa cells and theca walls. Significantly larger numbers of genes were differentially expressed in granulosa cells than in theca walls throughout development, and between LD and PO follicles than between ED and LF follicles. The most salient features were the downregulation of cell cycle genes in granulosa cells during both the ED-LD and LD-PO transitions and the upregulation of genes associated with inflammation, immunity, extracellular matrix remodelling and protection aganints toxic insult in both GCs and TCs, particularly during the LD-PO transition.
2014-03-15 | GSE52109 | GEO
Project description:Ovulation requires sequential molecular events and structural remodeling in the ovarian follicle for the successful release of a mature oocyte capable of being fertilised. Critical to this process is progesterone receptor (PGR), a transcription factor highly yet transiently expressed in granulosa cells of preovulatory follicles. Progesterone receptor knockout (PRKO) mice are anovulatory, with a specific and complete defect in follicle rupture. Therefore, this model was used to examine the critical molecular and biochemical mechanisms necessary for successful ovulation. Although PGR is not expressed in the cumulus cells or oocyte of the preovulatory cumulus oocyte complex (COC), it is well known that the COC responds to the cascade of gene expression changes that occurs in preovulatory granulosa cells. We used microarrays to identify putative ‘ovulation’ genes in preovulatory COCs at a time when PGR expression is maximal in granulosa cells (eCG + 8h hCG) and the preovulatory COC and follicle are undergoing the final changes necessary for successful ovulation.
2018-04-20 | GSE92436 | GEO