The first successful ovarian tissue transplant involving two sisters who are not twins has been carried out by doctors on the Continent, according to a study published today.

The sister who received the tissue, Teresa Alvaro, produced eggs which were fertilised by her husband's sperm, the journal Human Reproduction said.

Although the embryos did not develop properly, Mrs Alvaro is hopeful she will become pregnant in future.

The operation is the first to be carried out on two non-identical sisters, scientists in Belgium, where both sisters live, said.

A medical team, based in the US, hit the headlines in 2005 when Stephanie Yarber, who went through the menopause at 14, had a baby after her twin sister donated tissue.

In the latest case, Mrs Alvaro, from Bilzen, received the tissue of her sister Sandra, from Genk, after being left infertile by chemotherapy and radiotherapy.

In 1990, Mrs Alvaro, then aged 20, received chemotherapy and radiotherapy for an inherited blood disorder, beta-thalassemia. This was followed by a bone marrow transplant from her sister, who was 17 at the time.

The treatment and transplant were successful and Mrs Alvaro was cured.

In July 2005, aged 35, she contacted Professor Jacques Donnez, head of the department of gynaecology at the Catholic University of Louvain in Brussels, to ask about the possibility of receiving ovarian tissue from her sister.

After testing, Professor Donnez's team found the sisters were a good match, meaning immuno-suppressant treatment would not be necessary to stop the tissue being rejected.

Professor Donnez said: "Having already provided bone marrow in 1990, her sister (Sandra), who was now aged 32 and had never become pregnant, badly wanted to help her sister by donating some of her own ovarian tissue.

"Although the option of oocyte donation from the sister to the patient was discussed, the patient refused this option. She preferred a transplant because she wanted to be responsible' for the follicular maturation and considered that it was more natural than egg donation."

The sisters underwent the operation to transfer the ovarian tissue in February last year.

Sections of tissue were removed from Mrs Alvaro using laparoscopy and, in under a minute, were being sewn on to one of her sister's ovaries, also using laparoscopy. The sisters were discharged from hospital the next day.

Mrs Alvaro's periods began six months later. Tests on her hormone levels confirmed that her ovaries were functioning.

A year later, two eggs were removed from her ovary and fertilised with her husband's sperm using intracytoplasmic sperm injection (ICSI), a form of IVF (in-vitro fertilisation).

Experts believed ICSI had a greater chance of producing a pregnancy because her husband had a low sperm count.

One embryo developed to a two-cell stage while the second developed to a three-cell stage but both then stopped.

Professor Donnez said: "We do not know why the embryos ceased to develop, but this also happens during normal cycles of IVF. The patient is planning more IVF attempts."

He said it was too early to say whether the procedure could lead to a live birth.

He added, however, that the the procedure gave hope to women who had not had an opportunity to freeze either their eggs or their ovarian tissue.

Dr Robert Low, the most senior practising gynaecologist in Scotland described the latest development in Belgium as a "very exciting advance".

Dr Low, who is based at the Nuffield Hospital, Glasgow, said: "The exciting thing about infertility work is that on a regular basis we are able to offer some therapy that was not available the previous year."