Follicle Activation by Physical Methods and Clinical Applications

Devos, Melody; Demeestere, Isabelle; Grosbois, Johanne

doi:10.1007/978-3-030-47767-7_20

Cited by 2 publications

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“…Likewise, ovarian wedge resection and drilling have been used clinically to relieve inhibition of follicle growth and induce ovulation in PCOS patients, with promising results ( 253 ). The potential benefit of physically disruptive procedures has clinical relevance for boosting the activation of the follicular pool to rescue the residual follicles present in the ovaries of women with POI and diminished ovarian reserve ( 254 , 255 ).…”

Section: Primordial Follicle Recruitment Into the Growing Poolmentioning

confidence: 99%

Making a good egg: human oocyte health, aging, and in vitro development

Telfer

Grosbois

Odey

et al. 2023

Physiological Reviews

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Mammalian eggs (oocytes) are formed during fetal life and establish associations with somatic cells to form primordial follicles that create a store of germ cells (the primordial pool). The size of this pool is influenced by key events during the formation of germ cells and by factors that influence the subsequent activation of follicle growth. These regulatory pathways must ensure that the reserve of oocytes within primordial follicles in humans lasts for up to 50 years, yet only approximately 0.1% will ever be ovulated with the rest undergoing degeneration. This review outlines the mechanisms and regulatory pathways that govern the processes of oocyte and follicle formation and later growth, within the ovarian stroma, through to ovulation with particular reference to human oocytes/follicles. In addition, the effects of aging on female reproductive capacity through changes in oocyte number and quality are emphasized, with both the cellular mechanisms and clinical implications discussed. Finally, details of current developments in culture systems that support all stages of follicle growth to generate mature oocytes in vitro, and emerging prospects for making new oocytes from stem cells are outlined.

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Section: Primordial Follicle Recruitment Into the Growing Poolmentioning

confidence: 99%

Making a good egg: human oocyte health, aging, and in vitro development

Telfer

Grosbois

Odey

et al. 2023

Physiological Reviews

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“…Conversely, loosening of the ovarian ECM using a collagenase‐containing solution triggered follicle activation, while compression with exogenous pressure restored follicle dormancy ( Nagamatsu et al , 2019 ). Third, physically disruptive methods that loosen the tissue, such as ovarian fragmentation or drilling, are increasingly being used in clinical settings to release surface tension and disrupt the Hippo pathway, relieving inhibition of follicle activation and growth in women with premature ovarian insufficiency (POI) and polycystic ovary syndrome (PCOS), respectively ( Devos et al , 2022 ). Fourth, in vitro studies of isolated murine and primate follicles grown in alginate hydrogels of varying concentrations further confirm that a stiff environment is necessary to maintain primordial follicle quiescence and survival, but negatively affects secondary follicle growth, steroid production, and meiotic potential ( Xu et al , 2006 ; West et al , 2007 ; Hornick et al , 2012 ).…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal remodelling of the composition and architecture of the human ovarian cortical extracellular matrix duringin vitroculture

et al. 2023

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STUDY QUESTION How does in vitro culture alter the human ovarian cortical extracellular matrix (ECM) network structure? SUMMARY ANSWER The ECM composition and architecture vary in the different layers of the ovarian cortex and are remodelled during in vitro culture. WHAT IS KNOWN ALREADY The ovarian ECM is the scaffold within which follicles and stromal cells are organized. Its composition and structural properties constantly evolve to accommodate follicle development and expansion. Tissue preparation for culture of primordial follicles within the native ECM involves mechanical loosening; this induces undefined modifications in the ECM network and alters cell–cell contact, leading to spontaneous follicle activation. STUDY DESIGN, SIZE, DURATION Fresh ovarian cortical biopsies were obtained from six women aged 28–38 years (mean ± SD: 32.7 ± 4.1 years) at elective caesarean section. Biopsies were cut into fragments of ∼4 × 1 × 1 mm and cultured for 0, 2, 4, or 6 days (D). PARTICIPANTS/MATERIALS, SETTING, METHODS Primordial follicle activation, stromal cell density, and ECM-related protein (collagen, elastin, fibronectin, laminin) positive area in the entire cortex were quantified at each time point using histological and immunohistological analysis. Collagen and elastin content, collagen fibre characteristics, and follicle distribution within the tissue were further quantified within each layer of the human ovarian cortex, namely the outer cortex, the mid-cortex, and the cortex–medulla junction regions. MAIN RESULTS AND THE ROLE OF CHANCE Primordial follicle activation occurred concomitantly with a loosening of the ovarian cortex during culture, characterized by an early decrease in stromal cell density from 3.6 ± 0.2 × 106 at day 0 (D0) to 2.8 ± 0.1 × 106 cells/mm3 at D2 (P = 0.033) and a dynamic remodelling of the ECM. Notably, collagen content gradually fell from 55.5 ± 1.7% positive area at D0 to 42.3 ± 1.1% at D6 (P = 0.001), while elastin increased from 1.1 ± 0.2% at D0 to 1.9 ± 0.1% at D6 (P = 0.001). Fibronectin and laminin content remained stable. Moreover, collagen and elastin distribution were uneven throughout the cortex and during culture. Analysis at the sub-region level showed that collagen deposition was maximal in the outer cortex and the lowest in the mid-cortex (69.4 ± 1.2% versus 53.8 ± 0.8% positive area, respectively, P < 0.0001), and cortical collagen staining overall decreased from D0 to D2 (65.2 ± 2.4% versus 60.6 ± 1.8%, P = 0.033) then stabilized. Elastin showed the converse distribution, being most concentrated at the cortex–medulla junction (3.7 ± 0.6% versus 0.9 ± 0.2% in the outer cortex, P < 0.0001), and cortical elastin peaked at D6 compared to D0 (3.1 ± 0.5% versus 1.3 ± 0.2%, P < 0.0001). This was corroborated by a specific signature of the collagen fibre type across the cortex, indicating a distinct phenotype of the ovarian cortical ECM depending on region and culture period that might be responsible for the spatio-temporal and developmental pattern of follicular distribution observed within the cortex. LARGE SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION Ovarian cortical biopsies were obtained from women undergoing caesarean sections. As such, the data obtained may not accurately reflect the ECM distribution and structure of non-pregnant women. WIDER IMPLICATIONS OF THE FINDINGS Clarifying the composition and architecture signature of the human ovarian cortical ECM provides a foundation for further exploration of ovarian microenvironments. It is also critical for understanding the ECM–follicle interactions regulating follicle quiescence and awakening, leading to improvements in both in vitro activation and in vitro growth techniques. STUDY FUNDING/COMPETING INTEREST(S) Medical Research Council grant MR/R003246/1 and Wellcome Trust Collaborative Award in Science: 215625/Z/19/Z. The authors have no conflicts to declare. TRIAL REGISTRATION NUMBER N/A.

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Follicle Activation by Physical Methods and Clinical Applications

Cited by 2 publications

References 66 publications

Making a good egg: human oocyte health, aging, and in vitro development

Making a good egg: human oocyte health, aging, and in vitro development

Spatio-temporal remodelling of the composition and architecture of the human ovarian cortical extracellular matrix duringin vitroculture

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