Female birds able to ‘quality control’ sperm to influence the paternity of offspring

  • Scientists from the University of Sheffield have created 3D images of female birds’ reproductive systems for the first time
  • The researchers discovered a feature of sperm storage tubules in the birds’ reproductive tract that may allow them to select the best sperm to fertilise their eggs
  • The discovery could inform new research on fertility and IVF treatment

Image of a zebra finch

Researchers have discovered a feature of female birds’ reproductive systems that potentially allows them to select sperm and influence who fathers their chicks.

The scientists, from the University of Sheffield, used 3D imaging techniques to reveal a previously unknown structural feature in the zebra finch - a constriction at the opening of its sperm storage tubules.

This constriction may act as a gate, allowing female birds to perform ‘quality control’ on sperm that enter their reproductive tract after mating, influencing the paternity of their offspring and increasing the success rates of breeding attempts.

The discovery of the constricted opening suggests that sperm storage tubules act as a filtering system, allowing sperm that meet certain criteria to enter, while rejecting others. Ultimately, when the egg is ready to be fertilised, the pre-selected set of stored sperm is released.
By understanding how the birds perform this quality control on sperm after mating we can develop strategies to incorporate these selection criteria into artificial insemination and IVF in humans, thereby improving their success.

This may also be particularly important in captive breeding programmes where the availability of fertile individuals is low and assisted reproductive technology plays an important role in sustaining the population.

Dr Tania Mendonca, who conducted this research at the University of Sheffield, said: “The advantage of having an influence on paternity would be to ensure healthy offspring with the best chance of survival. Unlike sperm, eggs are a limited resource and it only takes one sperm to fertilise the egg - so there is an incentive for the female to ensure that the available egg is not fertilised by ‘poor quality’ sperm which could potentially result in an unsuccessful breeding attempt.”

This is the first time these storage organs have been imaged in 3D. It was made possible using a novel application of an imaging technique called selective plane illumination microscopy, or ‘SPIM’, developed for this purpose by a collaboration between the University of Sheffield’s Departments of Animal and Plant Sciences and Physics and Astronomy.

Although this study was conducted on birds, a number of other female animals across the animal kingdom - from reptiles to mammals - can store sperm in specialised organs. The findings therefore shed light on why this ability to store sperm evolved and how the reproductive cells interact with each other during sperm storage.

Additional information

The full paper, 'Sperm Gatekeeping: 3D Imaging reveals a constricted entrance to zebra finch sperm storage tubules' is available to view here: https://www.sciencedirect.com/science/article/pii/S0006349519309002

The University of Sheffield

With almost 29,000 of the brightest students from over 140 countries, learning alongside over 1,200 of the best academics from across the globe, the University of Sheffield is one of the world’s leading universities.

A member of the UK’s prestigious Russell Group of leading research-led institutions, Sheffield offers world-class teaching and research excellence across a wide range of disciplines.

Unified by the power of discovery and understanding, staff and students at the university are committed to finding new ways to transform the world we live in.

Sheffield is the only university to feature in The Sunday Times 100 Best Not-For-Profit Organisations to Work For 2018 and for the last eight years has been ranked in the top five UK universities for Student Satisfaction by Times Higher Education.

Sheffield has six Nobel Prize winners among former staff and students and its alumni go on to hold positions of great responsibility and influence all over the world, making significant contributions in their chosen fields.

Global research partners and clients include Boeing, Rolls-Royce, Unilever, AstraZeneca, Glaxo SmithKline, Siemens and Airbus, as well as many UK and overseas government agencies and charitable foundations.

Contact

For further information please contact:

Emma Griffiths
Media and PR Assistant
The University of Sheffield
0114 222 1034
e.l.griffiths@sheffield.ac.uk