Fertile Discussion

Made in the testes, sperm have a long journey ahead before emerging with the ability to fertilise an egg. From each testis’ seminiferous tubules, they travel to the epididymis, a long tightly-coiled tube where they continue to mature, before exiting through the vas deferens towards the ejaculatory ducts. A functional epididymis is critical to male fertility, and researchers recently discovered that this depends on communication with the testes during development. They identified a testicular protein, NELL2, which binds to a specific receptor in the developing epididymis, eventually unlocking production of the enzyme OVCH2 (in magenta in this slice through the epididymis), whose later interactions with a sperm surface protein, ADAM3, are essential for sperm maturation. Male mice lacking NELL2 are infertile, suffering from defects in sperm motility, suggesting that these complex interactions between testis and epididymis, known as lumicrine signalling, have major implications for research into male infertility.

Written by Emmanuelle Briolat

Emmanuelle Briolat

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A researcher specialising in visual signals in Lepidoptera, camouflage and the effects of light pollution, Emmanuelle’s writing covers a range of topics, from biomedical research to children’s books about moth defences.

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• Image from work by Daiji Kiyozumi and colleagues, Osaka University
• Immunology Frontier Research Center, Osaka University, Suita, Osaka
• Image copyright held by the original authors
• Research published in Science, June 2020