Testicular Aging and Male Fertility Mechanisms

Testicular aging is characterised by progressive alterations in the structure and function of the male gonad, leading to a gradual decline in fertility rather than an abrupt cessation. Key features include reduced spermatogonial stem cell proliferation, disruption of Sertoli and Leydig cell function, impaired steroidogenesis and alterations in the blood–testis barrier. At the molecular level, there is an accumulation of DNA damage, telomere shortening, epigenetic drift, increased oxidative stress and mitochondrial dysfunction. These changes culminate in decreased sperm count, motility and genetic integrity, while promoting germ cell apoptosis or ferroptosis. The testicular microenvironment is further compromised by chronic low‐grade inflammation and dysregulation of autophagic and apoptotic pathways. Globally, the impact of paternal age on reproductive outcomes and offspring health has driven efforts to identify biomarkers and develop targeted interventions. Emerging strategies include antioxidant supplementation, modulation of key signalling axes such as AMPK/mTOR, cell therapy with mesenchymal stem cell‐derived exosomes and pharmacological inhibitors of lipid peroxidation. Understanding the interplay between systemic ageing processes and organ‐specific mechanisms in the testis is essential to devise therapies that preserve male reproductive health and mitigate demographic challenges posed by delayed parenthood.

Research from Nature Portfolio

Recent studies using in vivo mammalian models have delineated how ageing affects germ cell development across both the testis and epididymis. Observations indicate that older males exhibit a 20 % rise in seminiferous tubule abnormalities, including germ cell depletion and failure of sperm release, while the remaining tubules show reduced spermatogonial proliferation. Concurrently, epididymal sperm from aged individuals display diminished concentration, abnormal morphology, reduced motility and increased DNA fragmentation, resulting in lower fertilisation and developmental success. These findings clarify that multiple cellular deficits, rather than endocrine changes, underpin the inexorable decline in male fertility with age.

Testicular Aging and Male Fertility Mechanisms publication trend

The graph below shows the total number of articles in testicular aging and male fertility mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

Blood–testis barrier (BTB): A physical and immunological barrier formed by tight junctions between Sertoli cells that shields developing germ cells from systemic circulation.

Spermatogenesis: The multi-stage process by which spermatogonial stem cells differentiate into mature spermatozoa within the seminiferous tubules.

Sertoli cell: A supporting somatic cell in the testis that nourishes germ cells, maintains the BTB and regulates the microenvironment for spermatogenesis.

Ferroptosis: A form of regulated cell death driven by iron-dependent lipid peroxidation and depletion of antioxidant defences.

Reactive oxygen species (ROS): Chemically reactive molecules derived from oxygen that, in excess, cause oxidative damage to lipids, proteins and DNA.

Autophagy: A cellular degradation pathway that recycles damaged organelles and proteins, often dysregulated during ageing.

Mitochondrial homeostasis: The maintenance of mitochondrial function and integrity through balanced biogenesis, dynamics and quality control mechanisms.

References

1. Multiple ageing effects on testicular/epididymal germ cells lead to decreased male fertility in mice. Communications Biology (2024).
2. Gss deficiency causes age-related fertility impairment via ROS-triggered ferroptosis in the testes of mice. Cell Death & Disease (2023).
3. Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Ameliorate Aging-Induced BTB Impairment in Porcine Testes by Activating Autophagy and Inhibiting ROS/NLRP3 Inflammasomes via the AMPK/mTOR Signaling Pathway. Antioxidants (2024).
4. Single‐Cell Transcriptomics Uncovers Core Signature for Regulating Mitochondrial Homeostasis During Testicular Ageing. Cell Proliferation (2024).