Sperm Research:
New Hope for Male Fertility Problems

A new method of studying sperm has been developed by an international team of researchers at Oxford University which marks a big step forward in identifying male fertility problems.

For the first time, the research shows that it is possible to introduce a synthetic gene (a transgene) directly into a normal, live animal in such a way that the gene is expressed in mature sperm. This method could be extremely important for fertility research because it allows many different aspects of gene function in sperm to be studied. This means that scientists can begin to understand the details of how the sperm works and how infertility may result when things go wrong.

This new approach promises to be a turning point because sperm cells cannot be cultured in a petri dish, unlike many cells of the body, because of their small size, unusual shape and short lifespan outside the body.

The study showed that the gene coding for a fluorescent green protein, originally taken from a jellyfish, could be introduced into sperm precursor cells within the testicles of a hamster, resulting in green, glowing sperm. Hamsters were used in the study because their sperm have many attributes in common with those of humans, and thus offer an excellent model for studying human sperm development and how defects in this process might result in infertility.

The scientist leading the study, Dr John Parrington of the Department of Pharmacology in Oxford, said: “We created green sperm to show this approach could work. But our real aim is to use this technique to study the function of genes that are important during fertilization and that may cause infertility if they become defective. That’s an important goal given that a recent study found that one in seven British couples have fertility problems and a third of these have an unknown cause.”

One of the areas that Dr Parrington’s team in Oxford are studying is the mechanism by which sperm activate eggs; that is, how a sperm by entering an egg triggers it to develop into an embryo rather than remaining in a state of suspended animation. This method of creating genetically modified sperm will aid their research, with important implications for understanding male infertility. It is also likely to be widely used by other scientists working in the field of gene function in sperm.

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Dr Parrington and his team have published their work in the Biology of Reproduction Journal.