LONDON - Doctors said on Monday they had transplanted human ovarian tissue into the muscles of mice to grow human eggs in a technique that could one day be used to retain the fertility of cancer patients.

Scientists from the Samuel Luenfield Research Institute at Mount Sinai Hospital in Toronto told the European Society of Human Reproduction and Embryology (ESHRE) conference in Bologna, Italy that it was the first time tissue from the human ovarian cortex has been grafted and yielded eggs. The ovarian cortex is the surface of the ovary which contains the follicles that produce the eggs.

"The possibility of preserving the ovarian cortex prior to surgery, drug or radiotherapy treatment offers new hope for young cancer patients," Dr Ariel Revel said in a statement released in London.

Revel and his colleague Dr Hila Raanani have used fresh and frozen ovarian tissue to successfully grow human eggs in mice. They now plan to see if the eggs retrieved from the mice muscle mature in the laboratory and if they are normal.

"If all goes well we could be ready to begin IVF (in vitro fertilisation) in the first patients in a year or so," said Revel.

Fertility centers are already freezing ovarian tissue and human eggs of women undergoing cancer treatment or other medical procedures which could damage their fertility. But freezing can damage the eggs, which are very fragile.

Transplanting the tissue back into the patients is also difficult. For cancer patients there is also the danger that the tissue may contain cancerous cells.

难点词汇：
　　 ovarian　卵巢的　　　　fertility　生殖能力　　　　　cortex　皮层，皮质
　　 yield　生长　　　　　　follicle　小囊, 滤泡　　　　 radiotherapy　电气透热疗法
　　 retrieve　重新得到　　 fragile　脆弱的，易碎的　　　transplant　移植
　　 cancerous　癌的