Sperm Function and Capacitation Regulation Mechanisms

Spermatozoa are highly specialised cells equipped to deliver paternal genetic material to the oocyte. Their journey from ejaculation to fertilisation involves precise regulation of motility, surface remodelling and exocytotic competence. Capacitation is a maturational process that occurs within the female tract or in vitro under defined conditions; it encompasses efflux of cholesterol, reorganisation of membrane microdomains, influx of bicarbonate and calcium ions and activation of cyclic AMP–dependent pathways. These changes prime the sperm for hyperactivated motility—a vigorous, asymmetric flagellar beat pattern—and for the acrosome reaction, an exocytotic event essential for zona pellucida penetration. Central regulatory mechanisms include protein phosphorylation at tyrosine and serine–threonine residues, dynamic redistribution of ion channels (notably calcium channels and the sperm-specific Na+,K+-ATPase α4 isoform) and modulation of intracellular pH and energy metabolism. Capacitation regulation is sensitive to environmental and pharmacological modulators, as well as to toxicants that perturb signalling cascades. An integrated understanding of these processes underpins advances in assisted reproduction, identification of male contraceptive targets and assessment of reproductive hazards posed by environmental agents.

Research from Nature Portfolio

Proteomic profiling of mouse sperm exposed to the insecticide fipronil revealed marked alterations in motility parameters, reductions in intracellular ATP and premature acrosome reactions. Quantitative mass spectrometry identified dysregulated expression of proteins involved in axoneme structure, cytoskeletal integrity and metabolic pathways, indicating that environmental toxicants can compromise capacitation by targeting key functional proteins. These findings advance our molecular understanding of how exogenous agents disrupt sperm competence and highlight candidate biomarkers for monitoring male reproductive health.

Sperm Function and Capacitation Regulation Mechanisms publication trend

The graph below shows the total number of articles in sperm function and capacitation regulation mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

Capacitation: A physiological transformation of sperm involving membrane and signalling changes that render the cell capable of fertilising an oocyte.

Acrosome reaction: Calcium-dependent exocytosis of the acrosomal vesicle enabling sperm to penetrate the zona pellucida.

Hyperactivation: A specialised motility pattern characterised by high-amplitude, asymmetric flagellar beating, essential for navigating the female reproductive tract and penetrating the oocyte investments.

Protein tyrosine phosphorylation: The addition of phosphate groups to tyrosine residues of proteins, a reversible modification that regulates capacitation-associated signalling cascades.

Lipid rafts: Cholesterol- and sphingolipid-rich membrane microdomains that organise signalling proteins and receptors during capacitation.

References

1. Proteomic analysis of fipronil-induced molecular defects in spermatozoa. Scientific Reports (2024).
2. Heat shock affects the Ca2+/calmodulin-dependent protein kinase II dynamic during bovine sperm capacitation and acrosome reaction. Frontiers in Cell and Developmental Biology (2025).
3. Ritonavir Has Reproductive Toxicity Depending on Disrupting PI3K/PDK1/AKT Signaling Pathway. Toxics (2024).
4. Role of tyrosine phosphorylation in sperm capacitation / acrosome reaction. Reproductive Biology and Endocrinology (2004).
5. The Na+ and K+ transport system of sperm (ATP1A4) is essential for male fertility and an attractive target for male contraception†. Biology of Reproduction (2020).
6. Reorganization of Lipid Rafts During Capacitation of Human Sperm1. Biology of Reproduction (2004).