By DAVID DERBYSHIRE

Last updated at 01:09 21 February 2008

The good news is that it actually exists. The bad news is that not every woman has one.

But, after nearly 60 years of searching, scientists said yesterday that they have definitively located the G-spot.

The fabled erogenous zone, which is thought to heighten pleasure during lovemaking, has been a source of heated debate ever since it was "identified" in 1950.

Despite plenty of anecdotal evidence in its favour from women, many doctors and scientists have insisted that it is a myth.

Italian researchers say, however, that ultrasound scans reveal anatomical differences between those who claim to have a G-spot and those who don't. The team, led by Emmanuele Jannini at the University of L'Aquila, found that tissue between the urethra and vagina was thickest in women who reported they had the erogenous zone.

The researchers also found tell-tale chemical markers in the area, New Scientist reports today. These markers include chemicals that process the nitric oxide responsible for male arousal.

Dr Jannini said this had allowed his team to develop a medical test to identify whether a woman has a G-spot.

"For the first time it is possible to determine by a simple, rapid and inexpensive method if a woman has a G-spot or not," said Dr Jannini.

Because the study was so small, he said his suspicion that a large proportion of women had no G-spot was only a guess.

An expert whose research team coined the term G-spot in 1981 disputed this estimate.

Beverley Whipple, of Rutger's University School of Nursing in New Jersey, said: "It's an intriguing study but it doesn't necessarily mean that women who don't experience orgasm don't have any tissue there."

Her studies have shown that all women describe some sensitivity in the area of the G-spot. It is also possible that women who experience more intense sexual pleasure have learned through practice, thereby altering their anatomy.

Studies of twins back the idea that women who say they have a G-spot are physiologically different.

In 2005, Dr Tim Spector, of St Thomas' Hospital in London, found that female arousal depended partly on genetic inheritance. "This [the Italian] study raises the possibility that local genital differences rather than purely genetic differences in brain responses or personality may be important," he said.

Dr Elisabeth Lloyd, from Indiana University and author of The Case of the Female Orgasm, said: "If Jannini's correlation does hold true, it would help explain the fact that most women do not reliably have orgasm with intercourse."

The G-spot was named after Ernst Grafenberg, a German gynaecologist who proposed its existence in 1950. The landmark Hite Report on Female Sexuality in 1976 suggested that the clitoris is largely responsible for orgasms in most women.