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Sperm Morphology – What is considered “normal”?


Understanding sperm morphology is key to being able to analyze whether the sperm present in a semen sample have any deformations that are making it difficult to conceive a pregnancy.

All men produce sperm cells which are in some way deformed or abnormal. For a sperm sample to be considered as normal, it needs to have a minimum percentage of sperm with correct shape and form.

According to the criteria laid out by the World Health Organization (WHO), a quantity equal to or above 4% of sperm with the correct morphology is considered within the normal range. If more than 96% of the sperm are abnormal, that is to say less than 4% with the correct shape, then the male is considered to have teratozoospermia.

Teratozoospermia is an condition which effects a man’s semen. It means that the majority of the sperm have an abnormal morphology, which can make the man sterile.

sperm abnormalities

Although a single sperm is only 0.05 mm long, it can have deformities in any of its parts. To study such details it is necessary to perform a semen analysis (sperm test).

  • Head: here we can find different types of deformities; sperm cells without heads (headless, or acephalic sperm), or heads that are too small (pinhead), misshapen, rounded, elongated, overly large or pear shaped. Other possible alterations that exist are sperm with two heads.
  • Neck (middle) piece: this could be asymmetrical, too thick, curved or misshapen.
  • Tail: the final part of the sperm. Sperm without a tail, with multiple tails, folded, broken and curled tails are some examples of the most common characteristics.
  • Mixed: when more than one part of the same sperm cell has abnormal morphology (head, neck and tail).

What is normal sperm cell morphology?

To analyze whether a sperm has a normal morphology, it should be evaluated for its three main parts: the head, middle neck piece and tail. To be considered normal, the head should be oval and smooth, with a regular outline attached to the middle piece, which should be slender and regular. The tail should have uniform thickness and be thinner than the middle piece.

sperm retrieval techniques

At Ovoclinic, we can perform different sperm retrieval techniques with the aim of selecting the best sperm cells for the fertilization, whether from a sample of ejaculate or using other methods in cases of azoospermia of different causes. In these cases, we can perform the retrieval through the epididymis: PESA (Percutaneous Epididymal Sperm Aspiration) or MESA (Microsurgical Epididymal Sperm Aspiration, or obtain the sperm via the testicles: TESA (Testicular Sperm Aspiration) or the TESE technique (Testicular Sperm Extraction, the surgical extraction of sperm from testicular tissue).

These treatments are indicated for patients with azoospermia or who have previously had  a vasectomy.

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