The production of high-quality oocytes requires precisely orchestrated intercellular communication. Extracellular vesicles (EVs) are cell-derived nanoparticles that play a vital role in the transfer of bioactive molecules, which has gained much attention in the field of diagnosis and treatment. Over the past ten years, the participation of EVs in the reproductive processes of oocytes has been broadly studied and has shown great potential for elucidating the intricacies of female reproductive health. This review provides an extensive discussion of the influence of EVs on oocytes, emphasizing their involvement in normal physiology and altered cargo under pathological conditions. In addition, the positive impact of therapeutic EVs on oocyte quality and their role in alleviating ovarian pathological conditions are summarized.
Humans ; Extracellular Vesicles/physiology* ; Oocytes/cytology* ; Female ; Animals ; Cell Communication/physiology*

Mitochondria serve as multifunctional powerhouses within cells, coordinating essential biological activities that are critical for cell viability, including material metabolism, signal transduction, and the maintenance of homeostasis. They support cells in adapting to complex and fluctuating environments. Oocytes, being the largest cells in multicellular organisms, contain a high number of mitochondria with unique structural characteristics. Mitochondria play active roles in the development and maturation of oocytes. A decline in mitochondrial function negatively affects both the quality and quantity of oocytes, thereby contributing to ovarian aging. However, the specific mechanisms through which mitochondrial dysfunction influences the progression of ovarian aging and impacts reproductive longevity remain unclear. Furthermore, medical strategies aimed at rejuvenating mitochondria to restore ovarian reserve and improve female reproductive potential may open new avenues for clinical treatment. In this review, we summarize the current understanding and key evidence regarding the role of mitochondrial dysfunction in ovarian aging and present emerging medical approaches targeting mitochondria to alleviate premature ovarian aging and enhance reproductive performance.
Humans ; Female ; Mitochondria/physiology* ; Ovary/physiology* ; Aging/physiology* ; Animals ; Oocytes/metabolism*

Bone morphogenetic proteins (BMPs) are multifunctional growth factors of the transforming growth factor β (TGF-β) superfamily. They regulate steroid secretion from mammalian granulosa cells, promote granulosa cell survival and proliferation, and inhibit follicular atresia, luteinization, and granulosa cell apoptosis, thereby promoting the development and maturation of mammalian follicles. At the same time, BMPs play an important role in embryonic morphogenesis, induction of uterine receptivity, and blastocyst attachment. This paper describes the effects of BMPs on mammalian follicular and embryonic development and the roles of BMPs in female reproduction, focusing on the process in which BMPs promote follicular maturation by regulating steroid secretion from granulosa cells during mammalian oocyte maturation. This review aims to provide a reference for further research on mammalian oocyte culture and improvement of reproductive efficiency in female animals.
Animals ; Embryonic Development/drug effects* ; Female ; Bone Morphogenetic Proteins/pharmacology* ; Reproduction/physiology* ; Humans ; Granulosa Cells/cytology* ; Oocytes

Melatonin,an endocrine hormone synthesized by the pineal gland,plays an important role in the reproduction.The growth and development of follicles is the basis of female mammalian fertility.Follicles have a high concentration of melatonin.Melatonin receptors exist on ovarian granulosa cells,follicle cells,and oocytes.It regulates the growth and development of these cells and the maturation and atresia of follicles,affecting female fertility.This paper reviews the protective effects and regulatory mechanisms of melatonin on the development of ovarian follicles,granulosa cells,and oocytes and makes an outlook on the therapeutic potential of melatonin for ovarian injury,underpinning the clinical application of melatonin in the future.
Animals ; Female ; Melatonin/pharmacology* ; Ovarian Follicle ; Oocytes ; Granulosa Cells/physiology* ; Mammals

Mammalian fertilization begins with the fusion of two specialized gametes, followed by major epigenetic remodeling leading to the formation of a totipotent embryo. During the development of the pre-implantation embryo, precise reprogramming progress is a prerequisite for avoiding developmental defects or embryonic lethality, but the underlying molecular mechanisms remain elusive. For the past few years, unprecedented breakthroughs have been made in mapping the regulatory network of dynamic epigenomes during mammalian early embryo development, taking advantage of multiple advances and innovations in low-input genome-wide chromatin analysis technologies. The aim of this review is to highlight the most recent progress in understanding the mechanisms of epigenetic remodeling during early embryogenesis in mammals, including DNA methylation, histone modifications, chromatin accessibility and 3D chromatin organization.
Animals ; Chromatin Assembly and Disassembly ; DNA Methylation ; DNA Transposable Elements ; Embryo, Mammalian ; Embryonic Development/genetics* ; Epigenesis, Genetic ; Epigenome ; Female ; Fertilization/physiology* ; Gene Expression Regulation, Developmental ; Histone Code ; Histones/metabolism* ; Male ; Mice ; Oocytes/metabolism* ; Spermatozoa/metabolism*

OBJECTIVETo evaluate the impact of sperm midpiece morphology observed under high-power microscope on embryo development following intracytoplasmic morphologically selected sperm injection.

METHODSMorphologically normal sperms from 57 patients undergoing intracytoplasmic sperm injection (ICSI) for male-factor infertility were selected microscopically (magnification of ×200 or 400) and subjected to motile sperm organellar morphology examination (MSOME) at high magnification of ×6000. According to the morphology of sperm medpiece, the sperms were divided into 3 groups, namely group A with a/b of 1-1.2, group B with a/b≥1.5, and group C with irregular morphology. The sperms in the 3 groups were intracytoplasmically injected in oocytes and the outcomes of the embryos were compared.

RESULTSGroups A, B, and C showed significant differences in the rate of ET-D3 top quality embryo (79.7% vs 55.6 % vs 33.3%) and implantation rate (43.2% vs 11.1% vs 0%), but not in the fertilization rate (73.3% vs 80.4% vs 63.5%), blastocyst formation rate (23.2% vs 22.2% vs 9.09%), cryopreservation rate (29.2% vs 25.0 % vs 13.0%), or D3 top quality embryo rate (35.3% vs 37.8% vs 18.8%).

CONCLUSIONSIn ICSI cycle, selecting morphologically normal sperms for intracytoplasic injection can increase the normal fertilization rate and top quality embryo rate on the transfer day and improve the implantation rate of the embryo.

Cryopreservation ; Embryo Implantation ; Embryonic Development ; Female ; Fertilization ; Humans ; Infertility, Male ; Male ; Oocytes ; Semen Analysis ; Sperm Injections, Intracytoplasmic ; Sperm Midpiece ; physiology

The effects of mouse oocyte vitrification on mitochondrial membrane potential and distribution were explored in this study. The collected mouse oocytes were randomly divided into vitrification and control groups. Ethylene glycol (EG) and dimethylsulphoxide (DMSO) were used as cryoprotectants in the vitrification group. The mitochondrial function and distribution in the oocytes were examined by using the fluorescent probes, JC-1 and Mito Tracker green. The results showed that the ratio of red to green fluorescence in mouse oocytes was significantly decreased after thawing in the vitrification group as compared with the control group (1.28 vs. 1.70, P<0.05). The percentage of polarized distribution of the mitochondria in oocytes was conspicuously reduced in the vitrification group when compared with the control group (31% vs. 63%, P<0.05). It was suggested that vitrification significantly affects the mitochondrial function and distribution in oocytes and reduces the potential of oocyte fertilization and embryo development.
Animals ; Cryopreservation ; methods ; Cryoprotective Agents ; pharmacology ; Dimethyl Sulfoxide ; pharmacology ; Ethylene Glycol ; pharmacology ; Female ; Fluorescent Dyes ; metabolism ; Membrane Potential, Mitochondrial ; drug effects ; physiology ; Mice ; Microscopy, Fluorescence ; Mitochondria ; drug effects ; metabolism ; Oocytes ; drug effects ; physiology ; Temperature ; Vitrification

BACKGROUNDIt is still unclear whether the vitrification procedure itself is associated with the incidence of abnormal DNA methylation during oocytes vitrification. The purpose of this study was to evaluate the epigenetic profile of mouse oocytes, which went through vitrification either at a mature stage or at an immature stage following in vitro maturation (IVM) by analyzing the global DNA methylation.

METHODSMetaphase II (M II) stage and germinal vesicle (GV) stage oocytes were collected from adult female mice and were vitrified respectively. The M II oocytes were assessed for cryo-survival and global DNA methylation. The GV oocytes were assessed for cryo-survival and only the surviving GV oocytes were cultured in vitro for subsequent assessment of global DNA methylation in mature oocytes. In vivo matured fresh M II oocytes without undergoing vitrification were used as control. The level of global DNA methylation in the M II oocytes was then examined by immunofluorescence using an anti-5-methylcytosine (anti-5-MeC) monoclonal antibody and fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse IgG under a laser scanning confocal microscope.

RESULTSIn terms of the effect of vitrification on global DNA methylation status in matured oocytes, in the M II-v group, all the examined oocytes (90/90) were found with hypermethylation, including 63.3% (57/90) of them displaying DNA methylation of a very high level, 25.6% (23/90) with a high level, and 11.1% (10/90) with an intermediate level, whereas in the GV-v group, all the matured oocytes (129/129) were also examined with hypermethylation, including 67.4% (87/129) of them displaying DNA methylation of a very high level, 23.3% (30/129) with a high level, and 9.3% (12/129) with an intermediate level. Statistically, it was similar between both groups, which were similar to the control: 68.6% (83/121) of fresh M II oocytes displayed DNA methylation of a very high level, 21.5% (26/121) with a high level, and 9.9%(12/121) with an intermediate level (P > 0.05). In terms of the effect of IVM on global DNA methylation status in matured oocytes, in the in vivo matured oocytes group, all oocytes examined (94/94) were found with hypermethylation, including 80.9% (76/94) displaying DNA methylation of a very high level and 19.1% (18/94) with a high level, whereas in the in vitro matured oocytes group, all oocytes examined (69/69) were also found with hypermethylation: 85.2% (56/69) of them displayed with DNA methylation of very high level, 11.9% (11/69) with high level, and 2% (2/69) with intermediate level. This result was similar to that in in vivo matured fresh M II oocytes (P > 0.05).

CONCLUSIONThe vitrification procedure at GV stage does not induce widespread alteration of global DNA methylation status of mouse oocytes subsequently matured in vitro.

Animals ; DNA Methylation ; physiology ; Female ; Fertilization in Vitro ; Mice ; Microscopy, Confocal ; Oocytes ; cytology ; metabolism ; Vitrification

OBJECTIVETo explore the correlation of human chorionic gonadotrophin (hCG) level in the follicular fluid on oocyte retrieval day with the number of oocytes retrieved, maturation rate, embryonic development, and pregnancy outcome in controlled ovarian stimulation cycles.

METHODSThe data of 311 IVF/ICSI-ET cycles from 2012 to 2013 was analyzed and stratified according to hCG level in follicular fluid on oocyte retrieval day (<7 nmol/L, 7-14 nmol/L, 14-21 nmol/L, and >21 nmol/L) determined with chemiluminescence method. The number of oocytes retrieved, oocyte maturation rate, fertilization rate, cleavage rate, available embryo rate and pregnancy rate were compared between the groups.

RESULTSIn the IVF/ICSI-ET cycles, the cycles with hCG level of 14-21 nmol/L in the follicular fluid on the day of oocyte retrieval had significantly higher oocyte maturation rate and fertilization rate than those in the other 3 groups (P<0.05), but the number of oocytes retrieved, cleavage rate, available embryo rate and pregnancy rate, though slightly higher, showed no significant difference from the other 3 groups (P>0.05). In the group with hCG level >21 nmol/L, the oocyte maturation rate and fertilization rate were significantly lower than those in the other 3 groups (P<0.05), and the available embryo rate and pregnancy rate were slightly lower without significant differences from the other 3 groups (P<0.05).

CONCLUSIONFollicular fluid hCG level on the day of oocyte retrieval is associated with oocyte maturation, fertilization, embryonic development potential, and IVF outcome. An excessively high follicular fluid hCG level on the day of oocyte retrieval may have negative effects on oocyte maturation and embryo development.

Adult ; Chorionic Gonadotropin ; chemistry ; Embryonic Development ; Female ; Fertilization in Vitro ; Follicular Fluid ; chemistry ; Humans ; Oocyte Retrieval ; Oocytes ; physiology ; Pregnancy ; Young Adult

Nano-cryopreservation may become a new way in the next generation of cryopreservation technology. However, research using nanoparticles in oocytes vitrification has not been reported in the literature. In this study, HA nanoparticles with different diameters were added into cryoprotectant and M II-stage porcine oocytes were vitrified by Cryotop. The results showed that nanoparticles improved the survival rate of cryopreserved M II-stage porcine oocytes, but the difference between nanoparticles with different diameters of was not significant. In order to study the mechanism of nano-cryopreservation, the cooling rate of cryoprotectant was measured by ultra-fast temperature measurement system and the melting enthalpy of cryoprotectant was measured by differential scanning calorimeter (DSC). The results showed that the adding of nanoparitcles could not increase the cooling rate of cryoprotectant, but could decreases the amount of ice crystals during freezing and warming. Therefore, the mechanical injury within and outside cells might be effectively reduced.
Animals ; Cell Survival ; physiology ; Cryopreservation ; methods ; veterinary ; Cryoprotective Agents ; pharmacology ; Durapatite ; pharmacology ; Female ; Fertilization in Vitro ; methods ; veterinary ; Metaphase ; Nanoparticles ; Oocytes ; cytology ; Swine ; Vitrification