Importance of Morphology of Sperm


Morphology refers to shape and size of sperm seen under microscope. Normal sperm have an oval head without a large vacuole, a midpiece and a 45 nm long uncoiled tail thinner than head and midpiece. Both head and tail are important in fertilization as head shape effect the sperm ability to dissolve the outer surface of egg and then fertilized the egg. Tail is important to provide its motility to reach the oocyte so it can fertilize.

Abnormal sperm may have misshappened head and cropped or double tail. Men with abnormally shaped sperm may also have no trouble causing a pregnancy. Having a large number of abnormally formed sperm in a sample and a low NF score are signs of a condition called teratozoospermia. The precise range can vary, but typically a normal or healthy sperm morphology range is between 4 and 14 percent. A score below 4 percent may mean it takes longer than normal to achieve pregnancy.

To assess sperm morphology, the sperm are examined under a microscope and the percentage of abnormally shaped sperm is estimated. It is important to know that all men produce abnormal sperm and as many as half of the sperm in a “normal” semen sample are abnormally shaped.

Sperm morphology is assessed using one of 2 sets of characteristics. Kruger criteria are strict and consider minute irregularities as abnormal. World Health Organization (WHO) criteria are more lenient and do not classify as many sperm as abnormal.

Relation between shape of sperm and morphology

There’s no relationship between the shape of a sperm and its genetic material. Once the sperm enters the egg, fertilization has a good chance of taking place. However, as some of the abnormalities in sperm shape may be the result of genetic disturbances, there may be some male offspring who will inherit the same type of morphology abnormalities as are found in their fathers’ sperm morphology.

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