Chapter 5, Page 2

Bovine Cervical Mucus Test

The bovine cervical mucus test is another form of testing for the ability of the sperm to penetrate and swim through cervical mucus, with the difference that, in this case, the mucus used is that of a cow (since this is commercially available in a test kit.) The sperm are placed in a column of cervical mucus and how far the sperm can swim forward through the column in a given amount of time is checked with the help of a microscope.

Sperm Viability or Sperm Survival Test

This is a simple test, which provides crude (but useful!) information on the functional potential of the sperm. The sperm are washed using the same method which is used for IVF (either a Percoll spin or sperm swim up) and the washed sperm are then kept in a culture medium in the laboratory incubator for 24 hours. After 24 hours, the sperm are checked under the microscope. If the sperm are still swimming actively, this means that they have the ability to "survive" in vitro for this period and this is reassuring. If, however, none of the sperm are alive after 24 hours, this suggest that they may be functionally incompetent.

Sperm Penetration Assay (SPA, Hamster Assay)

Since the basic function of a sperm is to fertilize an egg, scientists were very excited when they found that normal sperm could penetrate a denuded (zona-free) hamster egg. A hamster egg is obtained from hamsters and the covering (the zone) removed by using special chemicals. The egg are then incubated with the sperm in an incubator in the laboratory. After 24 hours, the eggs are checked to ascertain how many sperm have been able to penetrate the egg. The result gives a penetration score, which gives an index of the sperm's fertilizing potential. This is a very delicate technique and is not available in India. In any case, nowadays scientists the world over are quite disenchanted with the test, since the correlation between IVF results (the ability to fertilize human eggs) and the SPA (the ability to penetrate zona-free hamster eggs) is quite poor.

Other specialized semen tests include:

  • Testing for acrosomal status.
  • HOS test hypo-osmotic swelling test which tests for the integrity of the sperm membrane.
  • CASA computer assisted sperm analysis.
  • Hemizona assay.
  • Electron microscopy of sperm.
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Credits: How to Have a Baby: Overcoming Infertility