Meiotic progression is critically dependent on precise regulatory networks to ensure genomic stability. SMEK1 is recognized as a regulatory subunit of the protein phosphatase 4 complex. However, its potential phosphatase-independent functions in mammalian meiosis remain largely unexplored. Given the association of genetic variants near the SMEK1 locus with human infertility, we sought to define its specific role and mechanism in murine spermatogenesis. We generated a germ cell-specific Smek1 knockout mice model by crossing Smek1f/f mice with Stra8GFP-Cre mice. The phenotypic consequences were mainly assessed by histological analysis, chromosome spreading, and immunofluorescence staining. The molecular mechanisms were predominantly investigated using chromatin-immunoprecipitation, luciferase reporter assays, and co-immunoprecipitation analysis both invivo and invitro studies. Germ cell-specific ablation of Smek1 resulted in complete sterility due to a total arrest of spermatogenesis. The deficiency of Smek1 caused severe defects in prophase I, including an increased proportion of diplotene-stage spermatocytes, impaired synaptonemal complex dynamics, incomplete DSB repair, and a reduction in crossover. Notably, a subset of spermatocytes survived the initial checkpoint monitoring but arrested at metaphase I with a disrupted spindle structure and hyperactivation of the spindle assembly checkpoint. Mechanistically, we identified that SMEK1 functions independently of PP4 as a transcriptional repressor. It binds to the promoter of the deubiquitinating enzyme gene USP10. In the absence of SMEK1, increased USP10 protein stabilized BUBR1 (the core spindle assembly checkpoint component) and therefore delayed further progression beyond the metaphase I stage. Our study discovered a novel role for SMEK1 as a transcriptional regulator essential for meiotic progression. This SMEK1-USP10-BUBR1 pathway provides a fundamental mechanistic insight into the causes of male infertility and identifies a potential therapeutic target for human azoospermia and infertility.

With the recent increase in the incidence of male infertility, greater attention is being paid to male reproductive health. The causes of male infertility are complex, and damage occurring during any process from spermatogenesis to fertilization can affect sperm quantity and quality of the sperm. Mitochondria are the power sources of cells and help regulate cellular homeostasis and physiological function. Mitochondria play a crucial role in male reproduction. Mitochondria undergo dynamic changes during spermatogenesis, sperm maturation, and fertilization. Mitochondrial dynamics and mitophagy help regulate the structure and function of mitochondria by meeting the cellular energy requirements of sperm during reproduction and reducing levels of damaged mitochondrial DNA (mtDNA); the elimination of excess mtDNA during fertilization prevents the spread of genetic mutations. Stable mitochondrial function ensures the smooth occurrence and maturation of sperm, maintaining male fertility. Externally induced mitochondrial dysfunction can lead to an inadequate energy supply, oxidative stress, cellular apoptosis, and abnormal sperm structure formation, which can lead to male infertility. In this article, the mechanism through which mitochondrial dysfunction affects the entire process of male reproduction, from spermatogonial stem cell division to final fertilization, and leads to infertility is discussed in chronological order. This article explores potential therapeutic targets for improving male fertility through therapies targeting mitochondrial function to provide a reference for subsequent research and more precise treatment directions.

Multiple morphological abnormalities of the sperm flagella (MMAF) is a major cause of male infertility, but identified gene variants can only explain about 60% of clinical cases. Here, dynein axonemal intermediate chain 4 (DNAI4) is identified as an essential regulator of sperm flagellum morphogenesis. RT-PCR and western blot analyses indicate that expression of DNAI4 is enriched in murine testes. Dnai4 deletion in mice causes male-specific infertility due to oligoasthenoteratospermia with MMAF. Electron microscopy analyses revealed that DNAI4 deficiency resulted in an abnormal ultrastructure of sperm flagella, including disorganized mitochondrial sheaths, outer dense fibers and '9+2' axonemes, and missing inner dynein arms (IDA) and outer dynein arms. The IDA component DNAH10 was remarkably reduced in testes and sperm tails of Dnai4 knockout mice. Immunoprecipitation demonstrated an interaction between DNAI4 and the intraflagellar transport protein IFT144 within the testes. Other IFT-A members, including IFT140, IFT122 and IFT121, were downregulated in sperm tails following Dnai4 deletion. Taken together, these findings establish DNAI4 as an essential regulator of sperm flagellum assembly and mammalian spermiogenesis, operating through the regulation of IDA assembly and retrograde intraflagellar transport.

How can comorbidities associated with monogenic forms of male infertility systematically be identified? Via a framework that consists of seven sequential steps, gene-specific phenotyping protocols can be generated for all monogenic causes of male infertility. Infertility negatively impacts men's health. When loss of a single gene is causal for infertility (i.e. monogenic), the associated comorbidities are largely unknown. A framework was developed that allows the generation of gene-specific phenotyping protocols. The framework was applied to generate such protocols for two men, each with a different monogenic cause for their infertility. A multidisciplinary medical team formulated seven sequential steps to develop gene-specific phenotyping protocols. Gene-specificity was obtained by using a gene's expression pattern in the human body to identify tissues/cell types that show high levels of expression, as well as a literature search on the gene of interest, for potential morbidities. With these insights, tailored questionaries and tests are designed. We applied this framework to generate gene-specific protocols for two men in whom infertility was caused by the respective disruption of the genes MEI1 and DNAH17. These genes respectively show very high levels of expression in various types of immune cells and retinal cells. With gene-specific phenotyping protocols, we assessed the functionality of these cells in these men. Our framework facilitated the generation of two gene-specific phenotyping protocols that were used to systematically identify potential comorbidities associated with two forms of monogenic male infertility. Analyses of the gene expression in the human body identified immune cells (MEI1) and retinal cells and oligodendrocytes (DNAH17) as somatic cell types with high expression. Gene-specific phenotyping protocols contained targeted questions as well as clinical tests for these tissues/cell types. The questionnaires indicated no increased susceptibility to infections, allergies nor autoimmune disease (MEI1) or visual problems (DNAH17). The clinical tests comprised extensive immune profiling for the MEI1-participant and functional evaluation and imaging of the retinal cells of the DNAH17-participant. None of the test results indicated clinically relevant alterations at present. To identify true comorbidities, or lack thereof, more men with the same monogenic cause should be phenotyped. Not applicable. The Human Protein Atlas database was used to assess the expression pattern of the causal gene. This database only contains expression data in adult tissues. Potential comorbidities due to a developmental function of a gene can therefore be missed. In addition, comorbidities might develop later in life and might not be present during the phenotyping. Knowledge on the presence or absence of infertility-associated comorbidities allows clinicians to counsel patients on possible additional health risks for themselves and potential future offspring. As a consequence, medical care for infertile people extends beyond reproductive needs to general health. J.A.V. was funded by an Investigator Award in Science from the Wellcome Trust (209451) and by The Netherlands Organization for Scientific Research (918-15-667). The authors declare no conflicts of interest. N/A.

Introduction: Infertility is defined as the failure of a couple to conceive after one year of regular, unprotected sexual activity. Oligospermia is one of the causes of male infertility, when there are fewer than 20 million sperm per millilitre of semen. In Ayurveda, oligospermia is correlated with Kshina Shukra. Need of the study: A study on oligospermia is needed to address the growing concern of male infertility, which affects many couples and often has limited treatment options. Modern medicines such as Clomiphene citrate and Letrozole, which have long been used in the management of oligospermia, may be associated with adverse effects including dizziness, visual disturbances, flushing (skin redness), headaches, and nasal congestion. Vrushadi Vati, a herbal compound mentioned in Harita Samhita, contains Rishbhak (Malaxis muscifera), Bruhti (Solanum indicum), Kantakari (Solanum xanthocarpum), Pippali (Piperlongum), Gokshur (Tribulus terrestris), Kapikacchu (Mucuna pruriens), Shatavari (Asparagus racemosus), and Sharkara (white sugar), all of which possess aphrodisiac properties. No previous study has been conducted on Vrushadi Vati in Kshina Shukra (oligospermia). Aim: Evaluation of comparative efficacy of Vrushadi Vati versus Tab Clomiphene citrate in the management of Kshina Shukra (oligospermia). Materials and Methods: This will be a randomised controlled trial conducted at the Mahatma Gandhi Ayurved College, Hospital and Research Centre, Salod (H), Wardha, from March 2024 to February 2026. Patients will be randomly divided into two groups using a computerised method, each having 22 patients: Group A (n=22): Tab Clomiphene citrate (control group), Group B (n=22): Vrushadi Vati (experimental group). Treatment will be administered for 90 days. Follow-up will occur on the 30th, 60th, and 90th day, with parameters including sperm count and sperm motility assessed on the 30th and 90th days. Statistical analysis will be performed using the Wilcoxon signedrank test. Assessment parameters will be compared before and after treatment within each group by performing paired t-tests and between groups using unpaired t-tests. A p-value <0.05 will be considered statistically significant.

Varicocoele is a major cause of male infertility, yet its underlying molecular mechanisms and determinants of surgical efficacy remain unclear. This study aimed to identify key proteins involved in varicocoele-related infertility and to investigate the expression and functional role of ubiquitin-specific peptidase 2 in spermatozoa and spermatogenic cells. Ubiquitin-specific peptidase 2 expression in spermatozoa from varicocoele patients was analyzed before and after varicocelectomy by Western blotting. In vitro, ubiquitin-specific peptidase 2 was overexpressed or silenced in mouse GC-2 spermatocyte cells to assess mitochondrial autophagy (PINK1/Parkin pathway), autophagic flux, apoptosis, and reactive oxygen species. In vivo, a left-sided varicocoele rat model was established, and ubiquitin-specific peptidase 2 activity was inhibited by intratesticular injection of ML364. Testicular histopathology and sperm motility were evaluated. Ubiquitin-specific peptidase 2 protein expression was significantly reduced in spermatozoa after varicocelectomy. Ubiquitin-specific peptidase 2 overexpression enhanced PINK1/Parkin-mediated mitochondrial autophagy and protected spermatogenic cells from apoptosis, whereas ubiquitin-specific peptidase 2 knockdown impaired mitochondrial autophagy and increased cell apoptosis. In varicocoele rats, ubiquitin-specific peptidase 2 inhibition aggravated seminiferous tubule damage, reduced spermatogenic cell density, and impaired sperm motility. In human spermatozoa, ML364 treatment significantly decreased progressive motility without affecting sperm concentration. Ubiquitin-specific peptidase 2 is essential for maintaining mitochondrial quality control and spermatogenic cell survival in varicocoele by regulating PINK1/Parkin-mediated autophagy and oxidative stress, highlighting its potential as a biomarker and therapeutic target for varicocoele-related male infertility.

Infections are an important cause of male infertility, yet the effects of Mycoplasma hominis on specific semen parameters remain unclear. In this meta-analysis, we evaluated the impact of M. hominis infection on sperm quality. Comprehensive searches were performed in PubMed, Embase, Web of Science, Scopus, the Cochrane Library, Google Scholar, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) from their inception through October 2025. Standardized mean differences (SMDs) and 95% confidence intervals (CIs) were calculated. Egger's regression test and examination of funnel plots were applied to evaluate potential publication bias. Subgroup and meta-regression analyses were carried out to identify possible sources of heterogeneity, and sensitivity analysis was performed to verify the robustness of the overall estimates. Across 11 eligible studies, our analyses demonstrated that infertile men harboring M. hominis presented significantly lower sperm concentration (SMD = -0.815; 95% CI: -1.314 to -0.317; p = 0.001), progressive motility (SMD = -0.360; 95% CI: -0.683 to -0.037; p = 0.03), sperm viability (SMD = -0.831; 95% CI: -1.410 to -0.253; p = 0.005), and normal morphology (SMD = -0.631; 95% CI: -1.178 to -0.083; p = 0.02) compared to uninfected patients. Conversely, seminal fluid pH was consistently higher among infected subjects (SMD = 0.586; 95% CI: 0.167 to 1.006; p = 0.006). Subgroup and meta-regression analysis suggested that study geographic location and diagnostic technique contributed to the observed heterogeneity. However, no statistically significant publication bias was detected based on Egger's test (p = 0.10), and sensitivity analysis confirmed the robustness of the results. Collectively, these findings support a potential relationship between M. hominis infection and deteriorated semen quality. More rigorously designed prospective studies are needed to clarify causality and enhance diagnostic guidelines.

Re-evaluating the unknown causes of male infertility: Amebiasis as an emerging etiology.

Animal modeling methods for oligospermia: A review

The dose-response relationship between seminal plasma metal mixtures and oligo-astheno-teratozoospermia: a hospital-based case-control study.

Mechanisms of Traditional Chinese Medicine in regulating Nrf2-related signaling pathways for the treatment of Oligoasthenozoospermia: A review.

Blood-testis barrier-crossing extracellular vesicles for asthenozoospermia therapy via synergistic ATP replenishment and ferroptosis suppression.

BACKGROUND. Male infertility is a significant medical and social problem affecting approximately 7% of the male population worldwide. Genetic factors play a key role in the pathogenesis of spermatogenesis disorders, especially in azoospermia and severe oligozoospermia, but diagnostic and therapeutic approaches require constant updating in accordance with modern advances in molecular genetics. OBJECTIVE. To systematize current data on genetic causes of male infertility, diagnostic testing algorithms, and personalized therapeutic strategies for patients with various genetic variants of infertility. MATERIALS AND METHODS. Analysis of scientific literature on genetic aspects of male infertility was performed, including chromosomal abnormalities, molecular genetic defects, diagnostic methods, and modern treatment approaches using assisted reproductive technologies. RESULTS. The article presents a detailed classification of genetic causes of male infertility, including Klinefelter syndrome (detected in 10–15% of patients with non-obstructive azoospermia), Y-chromosome microdeletions (5–10% of cases of idiopathic azoospermia), monogenic diseases (cystic fibrosis, Kallmann syndrome, primary ciliary dyskinesia), and polygenic forms. Indications for various types of genetic testing depending on clinical manifestations are considered. Personalized therapeutic strategies for each nosological form are presented with emphasis on the use of microdissection testicular sperm extraction (micro-TESE), intracytoplasmic sperm injection (ICSI), and preimplantation genetic testing. It is shown that the success rate of sperm retrieval varies from <5% in AZFa deletions to 50–70% in AZFc deletions, while in hypogonadotropic hypogonadism, spermatogenesis induction is possible with success rates up to 90%. CONCLUSIONS. Genetically determined male infertility requires a multidisciplinary approach with mandatory genetic testing, personalized selection of therapeutic strategy, and comprehensive genetic counseling of couples. Preimplantation testing plays a critical role in preventing transmission of genetic abnormalities to offspring. Further development of genome editing technologies and in vitro spermatogenesis promises new opportunities for patients with genetically determined infertility.

Background.Varicocele is a common cause of male infertility, with ultrasound (US) serving as the primary diagnostic tool. Current practice relies on manual, subjective measurements of the spermatic vein, which are time-consuming and lack reproducibility. Developing automated tools is hindered by scarce annotated data and intrinsic US challenges like low contrast and high noise.Obejectives.This study aimed to: (1) develop and validate an efficient semi-automated annotation workflow; (2) establish the first performance benchmark for automated spermatic vein segmentation using deep learning; (3) critically evaluate the efficacy of state-of-the-art and customised segmentation models for this specific task.Methods.We proposed a semi-automated pipeline using the Segment Anything Model (SAM) with clinician refinement. Using the resulting dataset, we conducted a comprehensive benchmark, evaluating a baseline U-Net, advanced models (U-Net++, Attention U-Net, and RPA-UNet), and a proposed U-Net with deep supervision (UNet-DS). All models were assessed via leave-one-patient-out cross-validation and statistical tests.Results.The 'SAM+clinician' workflow showed excellent agreement with expert annotation (Dice Similarity Coefficient(DSC) = 92.66%; Kappa = 91.92%). In segmentation, the baseline U-Net achieved a mean DSC of 61.33%. Only Attention U-Net showed a statistically significant improvement (p= 0.0391). UNet-DS attained the mean DSC (64.65%) but this was not statistically significant (p= 0.0781). All models plateaued in a narrow range (DSC: 61%-65%), far below performance in mature US segmentation domains.Conclusion.This work validates an efficient semi-automated annotation solution and establishes the first performance benchmark for this task. Results reveal a distinct performance ceiling, indicating the primary barrier is the inherent data limitations, not model architecture. Future breakthroughs require a shift towards bespoke, physics-informed algorithms rather than applying generic deep learning models.

Asthenospermia is one of the most common causes of male infertility. In recent years, with changes in dietary habits, the number of obese patients with asthenospermia has been increasing, leading to a decline in male fertility. However, there remains a lack of safe and effective treatments for this condition. This study aims to confirm the efficacy and safety of acupuncture in obese patients with asthenospermia. In our randomized controlled trial, 72 patients will be randomly assigned (1:1) to receive either acupuncture treatment or sham acupuncture treatment. Each group will receive treatment two times weekly for twelve weeks with another twelve weeks for follow-up. The primary outcome is the progressive sperm motility (PR). And the secondary outcomes include PR plus non-progressive sperm motility, sperm concentration, semen volume, sperm morphology, body mass index, waist-to-hip ratio, and body fat percentage. We will also evaluate adverse events that occur during the acupuncture process. This study is expected to demonstrate whether acupuncture is effective and safe in the treatment of asthenospermia in obese men. The research findings will firstly provide new therapeutic evidence in treating asthenospermia of obese men and offer an alternative treatment options for improving the fertility of obese men. https://itmctr.ccebtcm.org.cn, identifier ITMCTR2025002025.

Y-chromosome microdeletions, particularly in the azoospermia factor c (AZFc) region, are a common genetic cause of male infertility. This study evaluates sperm retrieval rates (SRRs) and testicular histology across age groups in men with isolated AZFc deletions. We identified men with isolated complete AZFc microdeletions who underwent microdissection testicular sperm extraction from 2000 to 2024. Genitourinary pathology reports categorized histology as Sertoli cell-only, tubular atrophy, maturation arrest, or hypospermatogenesis. χ2 tests compared histology and SRR. Multivariable logistic regression assessed factors associated with successful sperm retrieval. Of 1473 patients who underwent Y-chromosome microdeletion testing, 72 with isolated AZFc microdeletions underwent microdissection testicular sperm extraction. Patients were stratified by age 35 years or younger (n = 51) and older than 35 years (n = 21). Overall, germ cells were identified in 59.7% of cases, with no difference between patients 35 years or younger (58.8%) and older than 35 years (61.9%; P = .81). The overall SRR was 50%, with no difference by the age group (≤35 years: 51.0%, older than 35 years: 47.6%; P = .80). On multivariable analysis, age older than 35 years (OR 0.82, 95% CI [0.28-2.40]) and the presence of spermatogenesis during biopsy (OR 1.66, 95% CI [0.59-4.69]) were not associated with SRR. Follicle-stimulating hormone levels between 12.4 and 24.0 mIU/mL were associated with higher SRR (OR 7.04, 95% CI [1.83-27.1]). Patient age was not a strong predictor of sperm retrieval success in men with complete AZFc deletion. Follicle-stimulating hormone levels within an intermediate range were associated with higher SRRs, suggesting that hormonal context may inform patient counseling. Reproductive urologists should counsel patients that age alone is unlikely to meaningfully influence sperm retrieval.

Oligo-astheno-teratozoospermia (OAT), a recurrent cause of male infertility, is the most frequent disorder of spermatogenesis with a predominantly genetic origin. Patients and mice bearing mutations in the ARMC2 gene exhibit reduced sperm concentration, multiple morphological defects, and impaired motility, defining a canonical OAT phenotype. Intracytoplasmic sperm injection (ICSI) is required to treat this condition; however, it is associated with a slightly increased risk of birth defects compared with natural conception, highlighting the need for novel targeted therapies. Here, in vivo testicular injection followed by electroporation of capped, polyadenylated naked messenger RNA (mRNA) was evaluated as a strategy to treat ARMC2 -related infertility in mice. mRNAs encoding reporter proteins were used to assess expression efficiency and kinetics using in vivo and in vitro 2D and 3D imaging. Reporter proteins were detected in germ cells for up to three weeks, demonstrating the feasibility of mRNA-based approaches. These results were compared with a non-integrative plasmid Enhanced Episomal Vector, which induced weak and transient expression in spermatogenic cells. Delivery of Armc2 mRNA restored morphologically normal and motile sperm in deficient males, capable of producing embryos via in vitro fertilization and ICSI. These findings provide proof-of-concept that mRNA electroporation can restore sperm motility and fertilizing potential, offering a novel strategy to correct monogenic male infertility.

Oligo-astheno-teratozoospermia (OAT), a recurrent cause of male infertility, is the most frequent disorder of spermatogenesis with a predominantly genetic origin. Patients and mice bearing mutations in the ARMC2 gene exhibit reduced sperm concentration, multiple morphological defects, and impaired motility, defining a canonical OAT phenotype. Intracytoplasmic sperm injection (ICSI) is required to treat this condition; however, it is associated with a slightly increased risk of birth defects compared with natural conception, highlighting the need for novel targeted therapies. Here, in vivo testicular injection followed by electroporation of capped, polyadenylated naked messenger RNA (mRNA) was evaluated as a strategy to treat ARMC2-related infertility in mice. mRNAs encoding reporter proteins were used to assess expression efficiency and kinetics using in vivo and in vitro 2D and 3D imaging. Reporter proteins were detected in germ cells for up to three weeks, demonstrating the feasibility of mRNA-based approaches. These results were compared with a non-integrative plasmid Enhanced Episomal Vector, which induced weak and transient expression in spermatogenic cells. Delivery of Armc2 mRNA restored morphologically normal and motile sperm in deficient males, capable of producing embryos via in vitro fertilization and ICSI. These findings provide proof-of-concept that mRNA electroporation can restore sperm motility and fertilizing potential, offering a novel strategy to correct monogenic male infertility.

Obstructive azoospermia (OA) is a significant cause of male infertility, with iatrogenic vas deferens injury after bilateral inguinal hernia repair representing a rare etiology. Outcomes of microsurgical vasovasostomy (VV) in this setting remain poorly defined. We conducted a retrospective case series of five patients with OA following bilateral inguinal hernia repair who underwent attempted laparoscopically assisted microsurgical VV. Inclusion criteria were azoospermia confirmed on at least two semen analyses, normal serum FSH and testosterone, preserved testicular volume, and female partners without major reproductive comorbidities. Demographic data, operative details, postoperative semen parameters, patency, and reproductive outcomes (spontaneous conception and assisted reproductive techniques - ART) were descriptively analyzed. Patency was defined as the presence of sperm in the ejaculate. Median patient age was 39 years (range 35-41), and median partner age was 35 years (range 30-40). Obstruction intervals ranged from 4 to 12 years. Four patients underwent laparoscopic dissection and bilateral VV (three two-layer, one one-layer), while one could not undergo anastomosis due to technical constraints. Operative times ranged from 150 to 420 minutes. One patient reported transient scrotal pain not requiring analgesia. Postoperative patency was achieved in three of the four anastomosed patients (75%), with sperm concentrations ranging from 3.0 Å~106/mL to 41 Å~106/mL. Four pregnancies were obtained: three through assisted reproductive techniques (ART) and one spontaneous. Among the ART cases, two required surgically retrieved sperm (patients without patency), whereas one used ejaculated sperm following VV. Importantly, a spontaneous pregnancy occurred in the patient with the highest postoperative sperm concentration (41 Å~106/mL) after a one-layer anastomosis. In this small case series, laparoscopically assisted VV proved technically feasible and allowed restoration of vasal patency in selected patients with OA after bilateral hernia repair. Beyond the potential for natural conception, this approach may facilitate the use of ejaculated sperm for ART, avoiding surgical sperm retrieval in selected cases. These findings reinforce the dual role of VV: restoring natural fertility in some patients and providing ejaculated sperm for ART in others.

Oligospermia, defined as a sperm concentration below the lower reference limit, is one of the most common causes of male infertility. According to the World Health Organization, a sperm concentration of less than 15 million/mL is considered oligospermia. Conventional treatment options include hormonal therapy and assisted reproductive techniques, which may be costly, invasive, and psychologically stressful. Homoeopathy, with its individualized and holistic approach, may offer a supportive role in the management of male infertility. A male patient presented with complaints of primary infertility. Repeated semen analyses revealed a significantly reduced sperm concentration consistent with oligospermia. The female partner was evaluated separately and no contributory abnormality was detected. A detailed homoeopathic case taking was performed, emphasizing mental generals, physical generals, and reproductive symptoms. The patient was followed up regularly with clinical assessment and serial semen analyses. Improvement was observed in general health, sexual vitality, and semen parameters, as evidenced by an increase in sperm concentration. The causal relationship between the intervention and outcome was assessed using the Modified Naranjo Criteria for Homoeopathy. This case report suggests that individualized homoeopathic treatment may be beneficial in improving semen parameters in cases of oligospermia.