• Question: can you modify a sperm cell to create a superhero?

    Asked by James to Laura on 17 Jun 2015.
    • Photo: Laura Wales

      Laura Wales answered on 17 Jun 2015:

      The sperm that fertilises the egg IS a superhero.

      The sperm that fertilises the egg is up against some fierce competition – millions of other sperm. Firstly, most of the sperm are abnormal – even in a “normal” sperm sample, 96% of the sperm can be deformed.

      Semen is ejaculated at about 28mph – that’s pretty fast for any tiny sperm cell.

      When on their epic journey to the egg, 50% of the sperm might get lost and swim in the wrong direction. Then they have to contend with the acidic environment in the female reproductive tract and the fittest ones can last a few days in this before getting to the egg.

      The sperm’s journey is only around 3 – 4 inches but it’s the equivalent of a human swimming the English Channel (around 20 miles).

      When the sperm reach the egg, in true superhero fashion, it “melts” the surface of the egg so it can get in. It does this by using enzymes in it the part of the head which dissolves the outer membrane of the egg.

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