A classical lay summary by Dr. Veronica Loyo-Celis, from The Ohio State University. 

The movement of the particles with charge (ions) inside and outside the cell is possible due to the presence of ion channels. In the sperm ion channels are the protagonist of every stage from spermatogenesis to fertilization.

After decades of studies, we now know that the flux of potassium, calcium, sodium, and chloride is essential for the correct functioning of the sperm. However, the study of ion channels in sperm began with the use of biochemical tools from which the chemical nature of these molecules was recognized.

In the 80's, studies about the functional expression of ion channels in sperm started when researchers from different parts of the world incorporated patch-clamp, a technique that permits measuring directly in the cell, the current that passes through the membrane.

It was not until 2006, when scientists measured the current from the remaining portion of cytoplasm in the flagellum (cytoplasmic droplet), this study overcame the technical barriers in the functional characterization of ion channels in the sperm.

The challenge now, with all the knowledge derived from the study of ion channels in sperm, is to design strategies that allow us to tackle fertility problems and, if possible, safeguard species in danger of extinction.

References

Kirichok Y, Navarro B, Clapham DE. Whole-cell patch-clamp measurements of spermatozoa reveal an alkaline-activated Ca2+ channel. Nature. 2006 Feb 9;439(7077):737-40. doi: 10.1038/nature04417. PMID: 16467839.

Darszon A, Labarca P, Nishigaki T, Espinosa F. Ion channels in sperm physiology. Physiol Rev. 1999 Apr;79(2):481-510. doi: 10.1152/physrev.1999.79.2.481. PMID: 10221988.

Sakmann B, Neher E. Patch clamp techniques for studying ionic channels in excitable membranes. Annu Rev Physiol. 1984;46:455-72. doi: 10.1146/annurev.ph.46.030184.002323. PMID: 6143532.