Scientists believe they have discovered the secrets of the female orgasm - after finding that the so-called "G-spot" actually exists.

Researchers in Italy hope the discovery could lead to new drugs to help women who have trouble having orgasms.

We have waited until now to really know the female anatomy

Dr Emmanuelle Jannini

The G-spot refers to an area a few centimetres inside the vagina on the side closest to a woman's abdomen.

The term was coined by Ernest Grafenberg in 1950 who it is named after.

The Skene glands are located in this area. They are believed to play a key role in producing the substance produced during female "ejaculation".

Chemical markers

Dr Emmanuele Jannini and colleagues at the University of L'Aquila set about trying to identify whether there were any chemicals which play a role in sexual functioning in the area where the G-spot is meant to be.

They chose to search for a protein or enzyme called PDE5. This protein plays an important role for men - too much of it prevents erections.

Dr Jannini found this protein in the vagina of five volunteers.

In tests on the bodies of 14 dead women, they found that the protein was mostly clustered around the G-spot.

However, in two of these subjects there were very low levels of PDE5. They were also found to have no Skene's glands.

This led Dr Jannini to conclude that these women would have been physically incapable of having an orgasm.

He suggested that women with high levels of PDE5 and large Skene's glands are most likely to have orgasms.

As a result, they believe that drugs like Viagra may have the greatest effect on these women.

Dr Jannini told New Scientist magazine: "It is ridiculous but true that we have waited until now to really know the female anatomy."

A number of studies have suggested that Viagra could help women to have orgasms.

'Female Viagra'

Pfizer, the manufacturers of the drug, have also carried out research in this area.

A spokeswoman said results from studies conducted so far had been promising.

The company is planning further research next year although a "female Viagra" remains a couple of years away.

"Research inside and outside Pfizer has begun to demonstrate greater success using Viagra to treat some women with female arousal disorder.

"We believe our internal results are sufficient enough to encourage larger confirmatory trials."

But she added that women should not take Viagra at the moment.

"Like all medication, it should only be taken as prescribed."

Viagra is currently not licensed for use in women and can therefore not be prescribed to them by doctors.