Biology of Reproduction最新文献

Embryo transfer is a key application of assisted reproductive technology (ART) in non-human primates (NHPs), underpinning research in reproductive biology, disease modeling, and conservation. The conventional approach-tubal embryo transfer (TET)-typically requires laparoscopy system and abdominal incision to expose the oviducts and reproductive tract for embryo transfer, and is associated with complex procedures, high cost, and cumulative reproductive tract injury following repeated surgeries. Moreover, implantation and pregnancy rates decline with increasing recipient age and surgical history, highlighting the need for a rapid, simple, and minimally invasive alternative. Here, using cynomolgus monkeys (Macaca fascicularis) as a model, we implemented a transabdominal uterine puncture (TUP) method. This technique involves the direct introduction of in vitro cultured embryos into the uterine cavity by means of an ultrasound-guided needle. In a cohort of 37 recipients, TUP yielded confirmed implantation in 19 animals (51.35%). Importantly, implantation and pregnancy outcomes in older animals and in those with prior reproductive surgeries were substantially higher than rates historically observed with TET. Gestation assessments and neonatal examinations revealed no discernible abnormalities or increased perinatal complications in offspring produced via TUP compared with controls, supporting the method as an efficient and safe embryo transfer strategy for NHPs.

The female reproductive system is a hormonally driven, immune-active, and structurally dynamic system in which estrogen signaling, inflammation, and extracellular matrix (ECM) remodeling interact to support essential reproductive processes. Cyclical changes in hormone levels, inflammation, and ECM turnover are essential for normal physiology, but dysregulation of these processes can give rise to chronic inflammation, fibrosis, and dysfunction across multiple reproductive tissues. Chronic immune activation, abnormal estrogen signaling, and maladaptive ECM remodeling engage in positive feedback loops that drive pathologies such as endometriosis, cervicitis, uterine fibroids, and intrauterine adhesions. Integrating preclinical rodent models with clinical findings, this review synthesizes current knowledge on the individual and interconnected roles of inflammation, estrogen signaling, and ECM remodeling and highlights diagnostic tools to improve early detection and therapy. The highlight of diagnostic tools focuses on emerging non-invasive imaging modalities, particularly magnetic resonance-based techniques, for in vivo visualization and quantification of inflammation, fibrosis, and tissue biomechanics in the female reproductive system.

In goats, embryo implantation is superficial, making endometrial receptivity a key determinant of pregnancy success. Although the NPM1/p53 nucleolar stress pathway is involved in endometrial receptivity in mice and humans, its role in ruminants remains unknown. Using early-pregnancy goat models, in vitro-induced goat endometrial epithelial cells (gEECs), and low-dose Actinomycin D (ActD) to trigger nucleolar stress, we investigated this signaling axis in goat endometrial receptivity. Compared with pre-receptive Day 10 endometrium, receptive Day 16 endometrium showed increased NPM1 expression in epithelial cells, accompanied by its translocation from the nucleolus to the nucleoplasm. Markers of nucleolar stress (p53, p21, MDM2) were upregulated, while pre-rRNA levels were reduced. In gEECs, low-dose ActD effectively activated the NPM1/p53 pathway, which was also activated during in vitro receptivity induction using estrogen, progesterone, and interferon-tau. Activation of this pathway by ActD increased receptivity markers (HOXA10, HOXA11, MSX1), recapitulating changes seen during receptivity induction, whereas Npm1 knockdown attenuated this effect. ActD treatment also activated Wnt/β-catenin signaling. Pretreatment with the Wnt/β-catenin inhibitor Adavivint markedly reduced ActD-induced upregulation of HOXA10 and HOXA11 proteins but did not affect p53 expression. Together, these results indicate that the NPM1/p53 nucleolar stress pathway promotes endometrial receptivity in goats, at least in part, through the Wnt/β-catenin pathway. This work expands understanding of endometrial receptivity in ruminants and provides a basis for further investigation of nucleolar stress in reproductive regulation.

The placenta establishes the maternal-fetal interface during pregnancy, enabling the selective exchange of nutrients and gases between maternal and fetal circulations. In humans and mice, this exchange surface is lined by multinucleated epithelial layers called the syncytiotrophoblast (SynT), which in the mouse placenta is organized into two distinct layers, SynT-I and SynT-II. SynT formation from trophoblast precursors requires epithelial plasticity to permit cell differentiation, fusion, and morphogenesis, while preserving epithelial integrity to maintain the maternal-fetal exchange barrier. However, the mechanisms that safeguard epithelial features during SynT development remain unclear. OVO-like 2 (OVOL2), a transcriptional repressor of mesenchymal-associated programs and key regulator of epithelial identity, is highly expressed in the mouse placenta and essential for its development. We hypothesized that OVOL2 promotes SynT lineage formation by restraining mesenchymal-associated transcriptional programs during trophoblast differentiation. To test this, placental development was examined following Ovol2+/- matings, and wild-type and Ovol2-deficient trophoblast stem cells were analyzed under stem conditions or differentiated with CHIR99021 to enrich for SynT lineages. SynT-I lineage development was disrupted in both Ovol2-deficient placentas and differentiating trophoblast stem cells, whereas SynT-II-associated differentiation appeared less severely affected. Chromatin profiling identified OVOL2 binding near genes associated with epithelial-to-mesenchymal transition, including Id1, Zeb1, and Vim, which were upregulated in Ovol2-deficient trophoblasts. Consistent with these observations, Ovol2-deficient cells showed elevated levels of mesenchymal markers such as ZEB1 and Vimentin and reduced levels of epithelial markers including E-cadherin. These findings identify OVOL2 as a critical regulator of SynT-I lineage formation and epithelial identity in the mouse placenta.

Elevated sperm DNA fragmentation index (DFI) is closely associated with adverse pregnancy outcomes, although the underlying mechanisms remain unclear. The fallopian tube is a key site for sperm selection and functional regulation, yet whether it differentially responds to sperm with varying DFI levels remains unknown. Reliable in vitro models for investigating sperm-fallopian tube interactions are currently lacking. Therefore, the development of reliable in vitro models to dissect the process of sperm selection by the fallopian tube will provide a new perspective for elucidating the mechanisms high DFI associated infertility. Primary epithelial cells isolated from the human fallopian tube isthmus were used to establish fallopian tube organoids (FTOs), and a suspension culture strategy was applied to reverse epithelial polarity, producing an apical-out configuration. Comprehensive histological, immunofluorescence, ultrastructural, and gene expression analyses confirmed that epithelial differentiation and barrier integrity were maintained following polarity reversal. A co-culture system was subsequently developed to enable direct sperm-epithelium contact. Apical-out FTOs supported sperm adhesion and improved sperm viability by reducing apoptosis and intracellular reactive oxygen species levels. Transcriptomic profiling revealed that normal sperm primarily induced pathways related to immune modulation and extracellular matrix remodeling, whereas high-DFI sperm induced inflammatory responses. Collectively, this study introduces and validates a novel apical-out human FTOs model that overcomes structural limitations of conventional systems. This platform enables relevant investigation of sperm-epithelium interactions and reveals that the tubal epithelium differentially responds to sperm DNA integrity, offering new insight into female tract potential implications in male factor infertility.

Mammalian fertility is dependent upon meiosis, a specialized cell division by which diploid progenitors undergo one round of DNA replication followed by two rounds of chromosomal segregation to produce haploid gametes. The germ line in the testis and ovary undergoes several rounds of mitotic divisions before ultimately transitioning to the meiotic cell cycle. This transition is achieved by replacing the mitotic cell cycle program with the meiotic one. Here, we discuss the molecular players that regulate the transition from mitosis to meiosis. In spermatogenesis, MEIOC, YTHDC2, and RBM46 form an RNA-binding complex that post-transcriptionally represses the mitotic cell cycle program, while in oogenesis, MEIOC inhibits mitotic cycling prior to meiotic initiation. STRA8 and MEIOSIN act as a transcription factor complex to drive meiotic initiation by upregulating genes involved in cell cycle progression and the unique chromosomal events of meiosis in oogenesis and spermatogenesis. These complexes are activated by upstream molecular players, including transcription factors, epigenetic regulators of chromatin structure, and extrinsic signaling factors, that form an intricate and reinforced molecular network to precisely regulate the transition from the mitotic to meiotic cell cycle. Here, we integrate current knowledge of the regulation of meiotic initiation in mammals and highlight key gaps in this regulatory program that remain to be explored.

Following injury from medical procedures or infections, the endometrium may fail to regenerate, leading to the formation of scar tissue that results in intrauterine adhesion, potentially disrupting normal endometrial function and contributing to infertility. Regenerative medicine is regarded as a promising solution to this concern, potentially providing effective treatment methods for the regeneration of injured human endometrium. Herein, we fabricated a degradable endometrial repair membrane (DERM) mainly composed of extracellular matrix, which acts as an intrauterine physical barrier and supports endometrial regeneration. In this study, we explored the role of DERM in epithelial transformation, anti-fibrosis, and angiogenesis using both an in vitro cell model and an in vivo electrothermal-induced rabbit IUA model. In vitro, the DERM effectively reduced the expression of fibrosis markers (FN1, COL1A1 and α-SMA) while promoting the expression of epithelial-related markers (CDH1 and CK19) in primary human endometrial stromal cells (HESCs) and angiogenesis-related factors (VEGFA and VEGFR2) in HUVECSs. The rabbit electrothermal injury model was used to mimic clinical electrosurgical adhesiolysis. In vivo, HE staining revealed DERM significantly accelerated endometrial regeneration, angiogenesis, and restored uterine functionality; Masson staining confirmed the deposition of collagen in endometrium of rabbits was notably reduced following the DERM treatment. Moreover, DERM remarkbly upregulated CDH1 and CK19 expression, and gradually degraded in the uterine cavity to avoid inflammatory irritation. In conclusion, the DERM facilitated the repair and regeneration of the endometrium, suggesting a promising new therapeutic approach for endometrial repair.

Male meiosis is the developmental process in which germ cells halve their chromosome number while continuing toward sperm formation. This review focuses on mechanistic studies of male meiosis in mouse and develops an epigenetic framework for this transition, centered on two key concepts. First, the foundation of meiosis is established ahead of meiotic entry. Prior to meiosis, germ-cell genes are poised and chromosomes are organized to support the upcoming meiotic program. Stage-specific signals and transcription factors then act on this prepared state to initiate meiotic gene expression. Second, meiosis reorganizes the germline in preparation for the post-meiotic spermiogenic program. In early prophase, nascent transcription remains low, allowing chromosomes to reorganize for recombination. Later, pachytene spermatocytes undergo an autosomal transcriptomic burst required for meiotic progression and post-meiotic development, while retrotransposon expression is controlled and unsynapsed sex chromosomes are silenced. Together, these concepts frame male meiosis as both the execution of a prepared developmental process and a critical window during which the germline genome is reshaped. This epigenetic trajectory connects gene regulation, chromosome organization, genome defense, and developmental timing to ensure production of functional sperm.

Because the blastocyst is a critical stage of early embryonic development, developmental abnormalities can serve as sensitive biomarkers of reproductive toxicity. This review focuses on the impact of various endocrine disrupting chemicals (EDCs) including phthalates, bisphenols, parabens and per- and polyfluoroalkyl substances on blastocyst formation, structure, and function. Murine blastocyst development models offer a controlled and reproducible platform to study cell differentiation, implantation potential, and epigenetic regulation. In vitro systems allow simulation of internal EDC concentrations found in human biological fluids, enabling dose-response relationships that reflect real world exposure. EDCs present in reproductive fluids such as follicular, oviductal, and endometrial fluid can impair oocyte quality and compromise embryonic development, even in morphologically normal embryos. Blastocysts exposed to EDCs during development show alterations in lineage specification markers (e.g., OCT4, SOX2, CDX2), cytoskeletal organization, and nuclear integrity, suggesting disruption of key developmental pathways. This review systematically reviews in vitro and in vivo evidence, along with proposed mechanisms of action, for each group of EDCs. Importantly, only studies reporting blastocyst formation rates were included to ensure relevance and comparability. The synthesis identifies common toxicity patterns, potential synergistic effects, and transgenerational consequences. The findings have direct implications for human fertility, particularly in the context of assisted reproductive technologies (ART), and highlight the need for improved regulatory frameworks and biomarker validation. Overall, the blastocyst emerges as a powerful tool for understanding and mitigating the reproductive risks associated with environmental chemical exposure.

In women of reproductive age, polycystic ovary syndrome (PCOS) is a widespread endocrine condition that is primarily connected to disrupted lipid metabolism. However, the cell-specific lipidomic signatures and their regulatory mechanisms in ovarian granulosa cells (GCs) of PCOS women remain elusive, particularly across clinical subgroups. We conducted quantitative lipidomics to profile luteinized GC lipid metabolism in PCOS subgroups. Non-overweight PCOS (NOP) patients underwent targeted validation via qRT-PCR and western blotting for lipid metabolism markers. Mechanistic studies employed SCD1-silenced human GC lines and a GC-specific SCD1 knockout mouse model, incorporating long-term fertility assessments. GCs from PCOS women, especially the NOP subgroup, displayed a unique lipidomic signature marked by suppressed biosynthesis and enhanced degradation, contrasting with circulating lipid profiles. Clinically, SCD1 expression correlated with improved embryo quality and implantation rates. In vitro, SCD1 deficiency triggered GC metabolic dysfunction, featuring reduced lipogenesis, elevated lipid peroxidation, iron accumulation, and mitochondrial impairment, which are characteristic of ferroptosis. In vivo, the GC-specific SCD1 deletion model exhibited an accumulation of secondary follicles, increased atresia, and progressive subfertility, alongside disrupted expression of lipid and iron metabolic regulators. Our study provides an integrated evidence chain suggesting that SCD1 acts as a regulator of lipid homeostasis in GCs. SCD1 deficiency contributes to metabolic disturbances that disrupt folliculogenesis, providing a potential mechanistic basis for the subtype-specific follicular dysfunction observed in NOP patients.