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Sperm Morphology Medically Reviewed

Last Updated: April 7, 2020

Definition - What does Sperm Morphology mean?

Sperm morphology refers to the size and shape of sperm. Sperm morphology is measured during a semen analysis, which is typically performed on men undergoing fertility testing. All men produce some degree of abnormal sperm, it is the ratio of abnormal to normal sperm that has the potential to impact fertility.

At least 4% of sperm should have normal morphology. This means that having at least 4% of sperm with a normal morphology is less likely to impact fertility.

FertilitySmarts explains Sperm Morphology

In addition to sperm morphology, a semen analysis also measures sperm count, concentration, motility and the volume of semen. The semen is analyzed under a microscope and the percentage of normal sperm is estimated. Strict (Kruger) criteria look at multiple sperm characteristics.

Features of a Normally Shaped Sperm

A typical sperm is shaped similar to tadpole:

  • An oval-shaped head
  • A defined cap on the top of the head (acrosome)
  • Neck with no abnormalities
  • Midpeice with no abnormalities
  • Long tail with no abnormalities

While abnormalities can occur in any of these areas, the importance is that these defects can impact the ability of sperm to locate and fertilize an egg. Examples include a misshapen head or a split tail.

Sperm Morphology

Abnormally Shaped Sperm Can Still Fertilize an Egg

Yet, abnormal sperm can still fertilize an egg. One study found that 22.9% of men with 0% normal morphology were able to conceive naturally, compared to 55.6% of the men with normal morphology. Additionally, these misshapen structures do not necessarily mean that there are problems with genetic material.

FertilitySmarts uses high-quality sources to support the facts within our content including peer-reviewed studies, academic research institutions, medical organizations, and governmental organizations. Learn more about how we ensure content is accurate by reading our .
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