For sperm to fertilise an egg they need to physically bind with the outer layer of the egg cell (the zona pellucida), and the head of the sperm then has to release enzymes that weaken and break through the tough outer coat of the zona. At this point the DNA carried in the sperm must enter and fuse with the DNA of the egg, which is when a viable cell with a new and unique collection of genetic material is formed. The Sperm Penetration Assay (SPA) tests whether sperm are able to penetrate and fertilize an egg, and this test is usually done when couples have low IVF fertilization rates without any other explanation.
- The SPA specifically measures the sperm ‘capacitation’, which is the capacity of the sperm to make the complex membrane changes necessary to bind to, penetrate, and then fertilize an egg, and capacitation is usually activated when sperm come into contact with a woman’s fertile mucus
How is the SPA done?
Specially prepared hamster eggs are used in this test and by measuring how well a man’s sperm penetrate the hamster eggs gives an accurate indication of his sperm’s ability to penetrate human eggs.
What does it tell you?
The results from an SPA test helps to identify men whose sperm aren’t able to fertilize eggs; these men will usually [/show_to]