Medsarticles. Medical Weblog

Sperm Penetration Assay or ‘Hamster’ Test

This is a test which uses hamster eggs to see whether the sperm can penetrate the eggs. Human sperm are able to penetrate hamster eggs but they cannot (thankfully!) develop into embryos. For the test the zona pellucida (outer layer) of the hamster eggs is removed and the doctors observe how many sperm can penetrate each egg. I doubt the value of this test because if the outer layer of the egg has been removed then it does not replicate the situation between a man and woman, where the sperm has to penetrate the outer layer of the egg for fertilisation to take place. It also suggests that you can compare a woman’s egg and a hamster’s egg. This test may result in totally worthless information and also involves the unnecessary use of another animal.

White Blood Cells

Immature sperm appear as round cells in the semen before they develop into their characteristic tadpole-like shape. White blood cells are also round and it is not easy to distinguish the two in a sample so special stains are used. It is important to know whether white blood cells are present because they can cause infertility. They could indicate an infection in the urinary tract. If white blood cells are noticed then further investigations are needed to rule out ordinary bacteria or an infection like Chlamydia.

Hormone Tests

Hormones may be tested and these could include FSH, LH, prolactin, testosterone and thyroid hormones. If FSH levels are high, it may indicate that there is a problem with sperm production in the testes. Giving high doses of testosterone as a medication can actually reduce the sperm count; so we come back once again to the idea of balance, with the hormone needing to be just right, neither too high nor too low. Some medications, such as clomiphene citrate and tamoxifen, have been used to treat male infertility but they are controversial and we do not know how beneficial they are.

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