Human Fertility Research Articles

Aberrant acetylation caused by a CDYL splicing mutation contributes to thin mid-piece related asthenoteratozoospermia and male infertility.

Acetylated tubulin is a hallmark of flagellar stability in spermatozoa, and studies have demonstrated the ability of CDYL to function as a tubulin acetyltransferase in spermatozoa. Of note, germline conditional knockout of Cdyl can lead to asthenoteratozoospermia and infertility in male mice. However, the role of CDYL gene in human fertility remains uncharacterized. Data were collected through in silico analysis for an infertile man with asthenoteratozoospermia of Han Chinese descent by performing whole-exome sequencing. Light and electron microscopy were used to characterize the sperm cells of the proband, and the pathogenicity of the genetic factors was determined by functional experiments. To overcome fertility problems, intracytoplasmic sperm injections were performed in the couple. Here, we recruited an infertile proband, born to first-cousin parents, displaying idiopathic asthenoteratozoospermia. Whole-exome sequencing identified a splicing mutation (c.103+1G>A) in CDYL, recessively cosegregating in the family. In vitro minigene assays demonstrated that the mutation resulted in aberrant alternative splicing. We found that CDYL co-localizes with Ac-tubulin along the flagella of human spermatozoa. In addition, the expression of Ac-tubulin was severely reduced in spermatozoa from the patient with CDYL mutation. Disruption in CDYL results in thin mid-piece related abnormal flagella morphology and decreased sperm motility. The primary manifestation of sperm ultrastructural abnormalities under the electron microscope is primarily characterized by disorder of axonemal protein complex and anulus. We demonstrated that a homozygous CDYL splicing mutation specifically induces a decrease in microtubule acetylation, resulting in thin mid-piece related asthenoteratozoospermia, providing a novel marker for genetic counseling and diagnosis of male infertility.

Association of Arachidonic Acid Metabolism Related Genes With Endometrial Immune Microenvironment and Oxidative Stress in Coupes With Recurrent Implantation Failure.

Alterations in lipid metabolism were reported to impact human fertility; however, there is limited evidence on the association of lipid metabolism with embryo implantation as well as the etiology of recurrent implantation failure (RIF), especially regarding arachidonic acid metabolism. Experimental verification research (16 RIF patients and 30 control patients) based on GEO database analysis (24 RIF patients and 24 control patients). The methods in bioinformatics included differential gene screening, functional enrichment analysis, protein-protein interaction network, cluster analysis, weighted gene co-expression network analysis, and so forth. RIF patients were recruited for the experimental validation section. The endometrial samples in the mid-luteal phase were collected and subjected to quantitative real-time PCR detection. Genes related to oxidative stress were differentially expressed and 17 different types of immune cells exhibited diverse infiltration in three RIF subgroups with different arachidonic acid metabolism. HPGDS, ALOX12, and TBXAS1 showed a strong positive correlation with the infiltration of NK cell, on the contrary, GGT6, PLA2G12A, and PTGS2 showed a strong negative correlation. The overall expression of AAMRGs was positively correlated with the infiltration of activated CD8 T cell, macrophage, natural killer cell, and T follicular helper cell. The cluster of arachidonic acid metabolism-related genes (AAMRGs) was abnormally expressed and positively associated with excessive oxidative stress as well as extensive infiltration of immune cells, including NK cells among RIF patients. Considering the high heterogeneity of the etiology of RIF, our study utilized the expression of AAMRGs as a typing basis to provide a new understanding of endometrial receptivity from the perspective of lipid metabolism and immune regulation in unexplained RIF couples, providing directions for its etiology and future basic research.

G v Human Fertilisation and Embryology Authority [2024] EWHC 2453 (FAM): two distinct routes to posthumous fertility treatment.

G v Human Fertilisation and Embryology Authority [2024] EWHC 2453 (FAM): two distinct routes to posthumous fertility treatment.

Lycopene in male infertility.

Male infertility is a major concern around the world, and efforts to find effective therapies to improve reproductive results are continuing. Factors such as genetics, hormonal disorders, lifestyle, and environmental pollutants have been mentioned as the pathoetiology of male infertility. The treatment of male infertility is far from optimal despite the recent signs of progress provided by assisted reproductive technology. Therefore, many efforts are being made to improve the therapeutical approaches to male infertility, which generally target the factors involved in the pathophysiology of the disease. Lycopene is a naturally occurring pigment belonging to the carotenoid family, which imparts a vibrant red color to various fruits and vegetables. It is widely assumed that lycopene may be an optimal option for the improvement of male fertility, however, the verification its therapeutic potential in male infertility has not been comprehensively reviewed. The study discusses the ability of lycopene to improve semen parameters, including sperm morphology, and motility which are important determinants of male reproductive health. Moreover, lycopene's capacity to regulate sex hormones, such as testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which play crucial roles in sperm production and maturation is explained. Additionally, lycopene effects on specific signaling pathways involved in male fertility, including prokineticin-2 (PROK2) and PI3K/Akt pathways, that influence sperm function are clarified. Furthermore, the impacts of lycopene as a potent antioxidant in defending against oxidative stress, a leading cause of male infertility, are presented. Overall, the results indicate that lycopene may have beneficial effects on improving male fertility by increasing sperm parameters, modulating sex hormones and signaling pathways, and providing antioxidant protection. Due to limited reports, additional clinical data is required to confirm the positive effects of lycopene on male fertility in humans.

Revisiting the J-Shape: Human Development and Fertility in the United States

Economic and social development are closely linked with fertility. Several studies have shown that the relationship follows an inverse J-shape: the association is negative at low and intermediate levels of development and reverses to become positive at high development levels. However, more recent research building on subnational and U.S. data found only mixed evidence for the inverse J-shape. In this article, we draw on subnational data on development and fertility in the U.S. states between 1969 and 2018 to examine the relationship between development and fertility. Using a longitudinal approach and addressing several criticisms of the fertility reversal hypothesis, our results support the inverse J-shaped pattern under most model specifications. However, this pattern might have vanished since the 2007–2008 financial crisis. Our findings provide insights into the mechanisms that link development and fertility, showing that gender equality and economic uncertainty mediate the relationship between development and fertility.

Motile Cilia in Female and Male Reproductive Tracts and Fertility.

Motile cilia are evolutionarily conserved organelles. In humans, multiciliated cells (MCCs), assembling several hundred motile cilia on their apical surface, are components of the monolayer epithelia lining lower and upper airways, brain ventricles, and parts of the reproductive tracts, the fallopian tube and uterus in females, and efferent ductules in males. The coordinated beating of cilia generates a force that enables a shift of the tubular fluid, particles, or cells along the surface of the ciliated epithelia. Uncoordinated or altered cilia motion or cilia immotility may result in subfertility or even infertility. Here, we summarize the current knowledge regarding the localization and function of MCCs in the human reproductive tracts, discuss how cilia and cilia beating-generated fluid flow directly and indirectly contribute to the processes in these organs, and how lack or improper functioning of cilia influence human fertility.

Bisphenol A (BPA) as a Contributing Factor to Decreased Fertility in Humans: a Review of the Latest Evidence

Bisphenol A (BPA) as a Contributing Factor to Decreased Fertility in Humans: a Review of the Latest Evidence

Establishment of a mouse model of ovarian oxidative stress induced by hydrogen peroxide.

Oxidative stress, resulting from environmental changes, significantly affects female fertility. Developing a mouse model to study oxidative stress lays the groundwork for research into human reproductive health and livestock fertility. In this study, we established and evaluated an oxidative stress model by administering hydrogen peroxide (H2O2) to mice. ICR mice of similar age (7-8 weeks old) and average body weight (31.58 ± 1.12 g) were randomly assigned to four groups (A, B, C, and D). Group A served as the control and was injected with a saline solution, while groups B, C, and D received saline solutions containing 0.75%, 1.50%, and 3.0% H2O2, respectively, over one week. We measured the body weights of all mice before and after the experimental period. Our findings showed that the average body weight of mice in groups A and B increased, while groups C and D experienced weight loss. Group C showed a significantly lower average weight gain compared to groups A and B, and group D exhibited an even more pronounced reduction in weight gain. Although group D had a high mortality rate, there was no significant difference in mortality rates among groups B, C, and D. Serum malondialdehyde (MDA) content increased with higher concentrations of H2O2, with a significant difference noted between groups C and A. Catalase (CAT) activity in group B was significantly higher than in group A, while superoxide dismutase (SOD) activity in group C was notably elevated compared to groups A and B. Conversely, glutathione peroxidase (GSH-Px) activity in group C was significantly lower than in both group A and group B. Hematoxylin and eosin (HE) staining revealed changes in ovarian morphology and follicle dynamics. The percentage of atretic follicles in group C was significantly higher than in the control group, and group D had a significantly lower total number of healthy follicles compared to the untreated group. Increased H2O2 content resulted in a reduction of ovary size and an irregular appearance in group D. Based on our findings, treatment with 1.50% H2O2 effectively established an oxidative stress model in mice within 1 week. This model serves as a valuable reference for future clinical studies on oxidative stress and reproductive disorders in female animals and humans.

Identification and Characterization of Novel FSHR Copy Number Variations Causing Premature Ovarian Insufficiency.

Follicle stimulating hormone (FSH) is a key pituitary gonadotropic hormone implicated in human fertility and is crucial for folliculogenesis and recruitment of new antral follicles. Variations in its receptor, FSHR, can lead to diverse reproductive phenotypes including ovarian hyperstimulation syndrome (OHSS) and premature ovarian insufficiency (POI). This study reports a novel case of FSHR-related ovarian insufficiency in a patient with primary amenorrhea, subnormal AMH levels, and delayed puberty. Genetic exploration revealed two compound heterozygous intragenic deletions of FSHR. Specifically, the patient inherited a maternally derived deletion spanning exons 5-10 and a paternally derived deletion involving exons 3-6. Through chromosomal microarray analysis (CMA), exome sequencing, long-range PCR, and Sanger sequencing, we characterized the breakpoints and confirmed the compound heterozygous deletions. The findings reveal a complete loss of function of both FSHR alleles, contributing to the patient's POI phenotype. This case emphasizes the complexity of genotype-phenotype correlations in FSHR-related disorders and the role of CNVs in POI phenotypes. Although these events are rare, our results advocate for the inclusion of CNV detection in the diagnostic workup of POI to ensure accurate diagnosis and better patient management.

Effects of Zinc and Selenium Coadministration on Semen Parameters and Hormonal Profiles of Male Wistar Rats.

Zinc (Zn) and Selenium (Se) are essential dietary micronutrients or trace elements not produced by the body but required in small amounts for the maintenance of mammalian and human male fertility. The over supplementation of individual and combination of micronutrients in the sick and healthy populations could be the leading cause of prevalence of male factor infertility in the world. This study was designed to evaluate the possible effects of the graded independent doses of oral supplementation of Zn, Se and their co-administration on male reproductive hormones, sperm parameters and histological architecture of male wistar rats. Fifty (n=50) adult male wistar rats weighing between 150g-250g and randomly grouped into ten groups of five rats each were used for this research that lasted for six weeks. Group I, the control group, received normal rat chow and water ad libitum. The nine test groups (II-X), received graded doses of zinc sulphate ZnSO4 (II-IV: 50mg/kg,150mg/kg,300mg/kg), selenium dioxide SnO2 (V-VII; 100mg/kg,200mg/kg,400mg/kg), co-administration of ZnSO4 and SnO2 (VIII-X:50mg/kg ZnSO4+100mg/kg SeO2, 150mg/kg ZnS04+200mg/kg SeO2, 300mg/kg ZnSO4+400mg/kg SnO2). Serum testosterone (T), follicular stimulating hormone (FSH) and luteinising hormone (LH) was estimated using ELISA Hormone Test kits radio-immuno-assay technique. Semen parameters was analyzed for sperm count, motility, and morphology using the grading system as described by WHO (1999). Testicular histological architecture was established using animal tissue processing technique. Data obtained were analyzed using one-way Analysis of Variance (ANOVA) from SPSS version 22. Statistical significance was placed at P<0.05 and data expressed as mean ± standard error of the mean (SEM).Results obtained from the study showed significant increase in testosterone levels in all the Zn test groups compared to the control and significant decrease in the levels of FSH and LH in higher doses of Zn and Se supplements when compared to the control at p<0.05. There was significant reduction in sperm motility, count but increase sluggishness in Zn and co-administration of Zn and Se of all the test groups compared to the control. Photomicrograph of the testes showed tissue inflammation, germinal cells destruction and azospermia. This study showed that chronic single or combined over supplementation of the micronutrients zinc and selenium could cause male factor infertility in wistar rats.

Classification of Human Ovarian Follicle Morphology: Recommendations of the NICHD-Sponsored Ovarian Nomenclature Workshop

To develop a consensus on histologic human ovarian follicle staging nomenclature, provide guidelines for follicle density calculation, and assess changes due to fixation to enhance communication among clinicians and ovarian biology researchers in order to gain a deeper understanding of human fertility. Beginning in March 2021, the Ovarian Nomenclature Workshop's Follicle Classification Working Subgroup was organized by the Pediatric and Adolescent Gynecology program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). The Follicle Working Subgroup recommends consolidation and expansion of the current classification systems to include six stages of normal preantral follicles, five stages of normal antral follicles, as well as categories of corpus lutea, abnormal preantral follicles, abnormal antral follicles, and other distinct follicle types. The new preantral staging added intermediate stages (primordial, transitional primordial, primary, transitional primary, secondary, multilayer ovarian follicles). The antral follicle staging includes: early pre-selection, selection, dominance, and pre-ovulatory follicles. Abnormal preantral follicles include those with an abnormal oocyte (AMF-o), granulosa cells (AMF-g), or both (AMF-og). We suggest a uniform way of calculating mean follicle density in number of follicles/mm2. To establish a consensus in ovarian follicle terminology, the Ovarian Follicle Working Subgroup of the NICHD Ovarian Nomenclature Workshop standardized Follicle Staging Nomenclature and Follicle Density Calculating Systems so consistent common language can be used among ovarian biology researchers and clinicians.

Exploring the Complex Relationship between Psychological Stress and Fertility: Implications for Population Growth in Developing Countries

Uncontrolled population growth has raised serious concerns among future policymakers. Although fertility rate has declined substantially over time, in developing countries the rate is still very high. Most of these countries face serious issues such as; severe poverty, malnutrition, unemployment, homelessness, financial insecurity, and medical insufficiency, leading to psychological distress. This article explores the mechanisms of psychological stress and its potential effects on human fertility. An attempt is made to differ from the existing claim that stress is anti-steroidogenic. This counter was based on earlier studies on adaptation of acute stress and overcoming stress stimuli. Which have asserted that individual adaptive abilities can alter the negative outcome of psychological stress depending on genetic, environmental, and behavioural factors. One of such adaptations comes from mitochondrial efficiency. An extensive energy demand during stress is achieved through competitive mitochondrial biogenesis. Earlier studies have noted that psychological stress triggers mitochondrial biogenesis. Thus, theoretically, mitochondrial biogenesis may also contribute in augmenting quality of sperm. In conclusion, stress induced biogenesis of mitochondria may contribute in enhancing fertility. Future studies on the degree of psychological stress and its possible retaliation through mitochondrial biogenesis, and subsequent responses to metabolic, and mechanical pathways, would open new avenues in understanding human fertility.

Survey of in vitro fertilization add-ons in Japan (Izanami project).

To identify any correlations between evidence levels, adoption rates, and additional costs of in vitro fertilization (IVF) add-ons. Online survey. The survey was conducted in 621 assisted reproductive technology-registered facilities that are members of the Japanese Society of Obstetrics and Gynecology from December 22, 2021, to February 13, 2022. The survey included details regarding the specific add-on modalities employed and their associated costs; inquiries pertained to the fertility healthcare infrastructure in Japan before the implementation of the National Health Insurance scheme. The correlation between the adoption rate and cost of IVF add-ons and their evidence levels were analyzed. The evidence level of the add-on treatments was classified into Green, Amber, and Red categories based on the United Kingdom's Human Fertilisation and Embryology Authority and Cochrane systematic reviews. A total of 438 eligible responses were analyzed, with clinics constituting 70.9% of the respondents' facilities. A total of 18 add-ons were assessed, and 96.5% (423/438) of facilities used at least one add-on. A positive correlation of the adoption rate and an inverse correlation of the cost with the evidence level of the IVF add-on treatment were observed (not significant). Outpatient clinics, defined as medical facilities with no beds, had a significantly higher adoption rate (Amber, 65.7%; Red, 52.0%) of add-ons than other facilities, regardless of the evidence rating, although the costs were similar across all site attributes. Accumulating evidence on the efficacy and safety of add-ons will lead to the development of medical care with a high-cost benefit, as an increase in the adoption rate and a decrease in cost are expected when limiting to medical care with a high level of evidence.

Dynamics of Human Fertility, Environmental Pollution, and Socio-Economic Factors in Aral Sea Basin

One of the worst natural, economic, and social catastrophes caused by human activity is the Aral Sea crisis in Central Asia. The Aral Sea’s desiccation, which has an impact on the region’s overall sustainable development, human welfare, security, and survival, is what led to the problem. This study assesses the effects of economic expansion, population ageing, life expectancy, internet usage, and greenhouse gas emissions on the fertility rate in the countries that made up the Aral Sea basin between 1990 and 2021. Several econometric techniques were used in this study, including Pooled OLS (Ordinary Least Squares) with the Driscoll–Kraay estimating method, FMOLS (Fully Modified Ordinary Least Square), and DOLS (Dynamic Ordinary Least Square). Additionally, we used the Hurlin and Dumitrescu non-cause tests to verify the causal links between the variables. The empirical findings verify that a decrease in the fertility rate among women in the nations surrounding the Aral Sea occurs when the population of a certain age (women aged 15–64 as a percentage of the total population) grows and life expectancy rises. Greenhouse gas emissions (GHGs) also have an adverse effect on reproductive rates. Conversely, the region’s fertility rate may rise as a result of increased internet usage and economic growth. Furthermore, this study indicates that certain variables—aside from greenhouse gas emissions (GHGs)—have a causal relationship with the fertility rate.

Impacts of iodoacetic acid on reproduction: current evidence, underlying mechanisms, and future research directions.

In light of the undeniable and alarming fact that human fertility is declining, the harmful factors affecting reproductive health are garnering more and more attention. Iodoacetic acid (IAA), an emerging unregulated drinking water disinfection byproduct, derives from chlorine disinfection and is frequently detected in the environment and biological samples. Humans are ubiquitously exposed to IAA daily mainly through drinking water, consuming food and beverages made from disinfected water, contacting swimming pools and bath water, etc. Mounting evidence has indicated that IAA could act as a reproductive toxicant and bring about multifarious adverse reproductive damage. For instance, it can interfere with gonadal development, weaken ovarian function, impair sperm motility, trigger DNA damage to germ cells, perturb steroidogenesis, etc. The underlying mechanisms predominantly include cytotoxic and genotoxic effects on germ cells, disturbance of the hypothalamic-pituitary-gonadal axis, oxidative stress, inhibition of steroidogenic proteins or enzymes, and dysbiosis of gut microbiota. Nevertheless, there are still some knowledge gaps and limitations in studying the potential impact of IAA on reproduction, which urgently need to be addressed in the future. We suppose that necessary population epidemiological studies, more sensitive detection methods for internal exposure, and mechanism-based in-depth exploration will contribute to a more comprehensive understanding of characteristics and biological effects of IAA, thus providing an important scientific basis for revising sanitary standards for drinking water quality.

The Influence of Human Capital on Fertility Intentions: The Moderating Role of Satisfaction with Leave Policies

In recent years, fertility has received much attention in the context of globalization. This study attempts to assess the influence of human capital on fertility intentions and to examine the moderating effect of satisfactory leave policies between human capital and fertility intentions across different genders. A questionnaire-based survey was conducted in four provinces of China, namely Guangdong, Shandong, Henan, and Sichuan. The results show a positive influence of human capital on fertility intentions and a remarkable moderating effect of satisfaction with vacation policy between human capital and fertility intentions among men. However, there is no significant moderating effect for women. This study suggests that men show higher fertility intentions when they can take leave, which may be due to the expectation of better family support. Conversely, women face significant fertility challenges, which mitigates the impact of leave on their fertility intentions. The study's novelty is that it reveals the differential effects of leave policies on fertility intentions across genders, providing new insights into the gender dynamics of human capital and fertility intentions. Based on these findings, recommendations are proposed for creating a stable employment environment and implementing comprehensive job security measures tailored to women's fertility needs to reduce fertility losses and alleviate employment pressures.

The epidemiological declining in the human fertility rate in the arab world for 10 years period 2011–2021

Recently, there has been worldwide growing interest on profiling the human fertility of populations because there has been a noticeable global decline in fertility rate, leading to increased attention toward reproductive health and fertility.The decline in fertility of population of the Arab World was investigated for the 10 years period between 2011–2021. The Arab World was classified into three regional blocks; Block-1 Arabian Peninsula countries: Bahrain, Kuwait, Saudi Arabia, Oman, Qatar, United Arab Emirates (UAE), Yemen. Block-2 Fertile Crescent Arab countries: Iraq, Jordan, Lebanon, Syria, West Bank and Gaza. Block-3 African Arab countries: Algeria, Comoros, Djibouti, Egypt, Libya, Mauritania, Morocco, Somalia, Sudan, Tunisia. Data on fertility rates for the 10 years period between 2011–2021 were collected from the World Bank for Arab countries. Statistical analysis along with decline in the fertility rates were determined. Results: Fertility rates varied across Arab countries in 2011 and 2021, with notable decline ranging from 24.3% to 3.8%, except for Algeria, with zero decline. Countries that exhibited significant decline were Jordan (24.3%) followed by Iraq (22.2%) then Yemen (19.1%); Whereas, countries that exhibited slight fertility decline were Libya (3.8%), followed by Tunisia (4.5%), Lebanon (4.5%) and Kuwait (4.5%). On another note, lowest fertility rate was observed in UAE as maintained between 1.7% and 1.5% and the highest fertility rate was observed in Somalia as maintained between 7.3% and 6.3% for 2011 and 2021 respectively. Conclusion: The present study reveals the declining-trend in fertility rate across Arab countries, influenced by variable factors. Therefore, we recommend to the Council of the Health Ministries in the Arab-League to focus on investigating the fertility decline as an important parameter for public health in the Arab world to maintain natural balanced fertility rate.As some non-biological factors surrounding the Arabian region, such as instability, war, migration, the present study did not aim to include the influence of war and migration on fertility because both war and migration are non-biological external factors and both are not among the WHO criteria for fertility determination which based of the population growth rate of population under normal living conditions.

Association of Atrazine-Induced Overexpression of Aldo-Keto-Reductase 1C2 (AKR1C2) with Hypoandrogenism and Infertility: An Experimental Study in Male Wistar Rat.

Atrazine (ATZ, C8H14ClN5) is a widely used synthetic herbicide that contaminates drinking water. It is a known endocrine disruptor that disrupts various molecular pathways involved in hormone signaling, and DNA damage, and can cause reproductive disorders, including decreased fertility, and abnormal development of reproductive organs, as revealed in animal model studies. However, the effect of ATZ on steroidogenesis in the male reproductive system, especially reduction of ketosteroids to hydroxysteroids, remains unclear. This study investigated the toxicity of ATZ on the male reproductive system in the Wistar rat model, with an emphasis on its adverse effect on aldo-ketoreductase family 1 member C2 (AKR1C2). Male Wistar rats were administered ATZ for 56days (duration of one spermatogenic cycle) through oral route, at 20, 40 and 60mg/kg body weight (bw) doses. The results indicate that ATZ exposure affects the body weight, impairs sperm production, and decrease FSH, LH, and testosterone levels. Additionally, the down-regulation of key steroidogenic enzymes by ATZ disrupted the synthesis of testosterone, leading to decreased levels of this essential male hormone. On the other hand, the expression of AKR1C2 (mRNA and protein) in the testis was upregulated. The findings suggest that AKR1C2 plays a role in androgen metabolism. Furthermore, its overexpression may lead to alteration in the expression of genes in the connected pathway, causing an increase in the breakdown or inactivation of androgens, which would result in lower androgen levels and, thereby, lead to hypoandrogenism, as the combined effects of down-regulation of steroidogenic genes and up-regulation of AKR1C2. These findings reveal direct implication of disrupted AKR1C2 in male reproductive health and highlight the need for further research on the impact of environmental toxins on human fertility, ultimately providing for better patient care.

Sperm Metabolism.

Bioenergetics plays a crucial role in sperm functions, including motility, capacitation-related protein modifications, oocyte recognition and interaction, all of which are essential for fertilization. Sperm metabolism is recognized as flexible, responding to environmental cues and energetic demands during ejaculation, the journey along the female tract, and until fertilization. Recent studies suggest that sperm metabolic functions are relevant beyond fertilization and may influence zygote and embryo development, impacting paternal-derived effects on offspring development and health. In recent years, sperm metabolic functions and homeostasis have gained increasing interest in male reproduction research. Given the crucial implications of sperm metabolism on fertility-related processes, this field is of interest not only in human male fertility but also in livestock research, semen conservation, and assisted reproductive techniques. Newly developed assessment tools are allowing a better understanding of sperm metabolism under different conditions and identifying species-specific peculiarities. This review aims to discuss the current knowledge of mammalian sperm metabolism, focusing on species-specific features, changes during the sperm journey, and potential contributions to translational research and reproductive biotechnologies. Furthermore, we propose future perspectives on sperm bioenergetics research.

Spermatogenic Stem Cells: Core Biology, Defining Features, and Utilities.

The actions of spermatogenic stem cells (SSCs) provide the foundation for continual spermatogenesis and regeneration of the cognate lineage following cytotoxic insult or transplantation. Several decades of research with rodent models have yielded knowledge about the core biology, morphological features, and molecular profiles of mammalian SSCs. Translation of these discoveries to utilities for human fertility preservation, improving animal agriculture, and wildlife conservation are actively being pursued. Here, we provide overviews of these aspects covering both historical and current states of understanding.