Electrophysiology of Human Gametes: A Systematic Review

Oocytes and spermatozoa are electrogenic cells with the ability to respond to electrical stimuli and modulate their electrical properties accordingly. Determination of the ionic events during the gamete maturation helps to design suitable culture media for gametes in assisted reproductive technology (ART). The present systematic review focuses on the electrophysiology of human gametes during different stages of maturation and also during fertilization.

The reports published in the English language between January 2000 and July 2021 were extracted from various electronic scientific databases following the PRISMA checklist using specific MeSH keywords.

Subsequent to the screening process with defined inclusion and exclusion criteria, 60 articles have been included in this review. Among them, 11 articles were directly related to the electrophysiology of human oocytes and 49 physiology department to the electrophysiology of human spermatozoa.

Gametes generate electrical currents by ionic exchange, particularly Na⁺, K⁺, Cl^-, H⁺, Zn²⁺, Cu²⁺, Se²⁺, Mg²⁺, HCO₃^-, and Ca²⁺ through specific ion channels in different stages of gamete maturation. The ionic concentrations, pH, and other physicochemical variables are modulated during the gametogenesis, maturation, activation, and the fertilization process following gamete function and metabolism. The electrical properties of human gametes change during different stages of maturation. Although it is demonstrated that the electrical properties are significant regulators of cell signaling and are fundamental to gamete maturation and fertilization, their exact roles in these processes are still poorly understood. Further research is required to unveil the intricate electrophysiological processes of human gamete maturation.