It is said that in life the journey is more important than the destination.

And for sperm, that is certainly the case, according to a new scientific study.

Researchers have discovered that the sperm of infertile men is every bit as healthy as fertile men while it is still in the testicles.

But by the time it has travelled through a series of ducts and left the body it has become damaged, suggesting something odd and toxic is happening along its path to the outside.

The discovery offers new hope for men who struggle to become fathers even through IVF as well as hinting at a new cause of male infertility.

Jonathan Ramsay, consultant urologist of Imperial College London, who led the study, said: “When we looked at ejaculated sperm, we found that the extent of sperm DNA damage was much higher in infertile men than in fertile men, with roughly 15 per cent in fertile men, but 40 per cent in infertile men.

“It wasn’t a surprise to see greater DNA damage in ejaculates of infertile men. What we didn’t expect was the consistency in these results when we looked at sperm taken directly from the testicles of infertile men, we found that it was of similar quality to that of ejaculated, fertile sperm”.