Morphology simply means the appearance and structure of a biological entity. Sperm morphology, therefore, is the study of how sperm look under a microscope. Unhealthy-looking sperm can be impaired, so morphological data can help identify fertility problems.
A normal sperm has three basic parts. The tail propels the sperm, allows it to move around, and if it is lucky, get to an egg. The midpiece attaches the head to the tail. Inside the head is the genetic material necessary to give the fertilized egg half the chromosomes to make an embryo.
A human sperm normally has a long, thin tail, a slim midpiece, and a head with an oval shape. This is the optimum sperm morphology to navigate through the male testes, through vaginal mucus, and up through a woman's reproductive system. The force produced by the tail and the shape of the head also helps the winning sperm to wriggle into the egg for fertilization.
If a sperm does not have this optimum shape, it can be at a disadvantage when it comes to performing its basic function of getting to the egg. This is why fertility specialists examine fresh sperm from a client. Healthy men can have many abnormally shaped sperm in one ejaculate, but as long as some sperm with the correct morphology are present, the ability to father a child is not affected.
It is when most of the sperm present in a sample are abnormally shaped that fertility problems can arise. Each part of the sperm can be abnormal. The head, for example, can be unusually big or have a funny shape. Sperm may even have more than one head. The midpiece can be abnormally shaped, and the tail can have a coiled shape or a pronounced bend. Two tails can also be present on one sperm. Dead sperm appear different after a stain is applied as the stain enters only the dead cells.
Abnormal sperm can be caused by a serious problem in production, or they can be caused by damage after production. Permanent conditions are not usually treatable, but temporary problems with sperm morphology can be solved by treating the underlying disease. Examples of possible treatable conditions include drug use, infections, or circulatory problems in the testes.
As well as sperm morphology, a typical fertility examination will assess how well the sperm can move around, which is also more technically referred to as motility. The analyst also checks how many sperm are in the sample compared to a normal level. Even if one sample displays a significant issue with abnormal sperm morphology, another test a few weeks later can have a result within normal limits.