Sperm Penetration Assay
For this test, hamster eggs are used in place of female eggs because they are more readily available and are very similar to human eggs in structure. However, due to the difference in species, although sperm are able to penetrate the egg, further development cannot occur.
For this test, also known as the hamster zona-free ovum test, the hamster eggs have been specially treated to remove the outer layer of the egg (known as the zona) and to allow sperm to fuse to the egg.
As with the sperm mucus penetration test, the male partner will provide a semen sample. Collected sperm will then be processed and refrigerated for three days. After this time, once sperm have undergone capacitation (a process necessary for the sperm to be able to penetrate an egg), sperm are combined with numerous hamster eggs.
Once the sperm and hamster eggs have incubated for three hours, the eggs are then evaluated to determine how many eggs have been penetrated and by how many sperm. Men whose sperm is able to penetrate all hamster eggs with between six and 20 sperm per egg are thought to be fertile. The fewer sperm that are able to penetrate the eggs, the less fertile a man is deemed to be.
This particular test is especially helpful for couples considering IVF. If test results reveal sperm that cannot penetrate an egg, a couple may decide to use ICSI in order to ensure fertilization.
Interpreting the Results
If the results of your sperm penetration tests show abnormal sperm, IVF may be suggested to help you conceive. However, so long as there are no fertility problems indicated for the female, some couples may also want to consider using donor sperm with IUI.
It is important to note, though, that test results can be compromised if a semen sample has not been collected properly or if a sperm mucus penetration test is performed when a woman is not ovulating. Therefore it is important that you have these tests performed by fertility doctors who are experienced in sperm penetration tests.