Lausanne, Switzerland: Swedish researchers have found that teenage girls with Turner's syndrome still have follicles in their ovaries which may be capable of producing eggs. This discovery offers hope that Turner's syndrome girls may be able to have babies in the future.
Mr Julius Hreinsson, an embryologist in the Fertility Unit at Huddinge University Hospital, in Stockholm, Sweden, told the European Society of Human Reproduction and Embryology annual meeting at Lausanne today (Wednesday 4 July), that he and his colleagues had succeeded in obtaining ovarian tissue containing follicles from five teenage girls. The researchers had divided the tissue and then frozen it.
"To our knowledge this is the first time that follicles have been observed in ovarian tissue from patients with Turner's syndrome. Our findings give hope for the future infertility treatment of these girls," he told the meeting.
Turner's syndrome affects about one in every 3,000 girls. They are born with one X chromosome missing and usually their ovaries do not develop properly. It is thought that the primordial follicles that are present in their ovaries at birth, start to disappear rapidly, although it is not clear at what age this process starts. As a result, Turner's syndrome women are usually infertile and spontaneous pregnancies occur in only about 2-5% of them. However up to 30% do show some sexual development at puberty, which suggests that follicles are still in their ovaries as adolescents.
Mr Hreinsson and his colleagues used laparoscopy1 to take ovarian tissue from six girls, aged 12, 13, 15, 15, 17 and 19 who had come to the clinic asking that their ovarian tissue should be frozen (cryopreserved) for possible infertility treatment in later life. They successfully retrieved ovarian tissue containing follicles from five of the girls, but the 17-year-old was found to have no ovarian tissue. The density of the follicles in the tissue ranged from 1.5 to 128 follicles per cubic millimetre. In theory this means there was a total count of between 600 and 54,000 follicles in the cortex of the whole of the ovary
Mr Hreinsson said: "Our results show a rapid decline of follicular density between the age of 12 years and 19 years in the subjects we studied. In view of the limited number of subjects in our study, further research is needed to confirm our results. However, on the basis of our results, we would recommend that the biopsy be performed at a young age, for example between 12 and 14 years old.
"At the same time, we cannot ignore the serious ethical considerations involved in operating on young girls for the purpose of cryopreserving ovarian tissue to preserve fertility. Careful attention must be given to informing the girls and their parents about the implications of the procedure and the chances of success later on."
Other researchers have shown that it is possible to transplant cryopreserved ovarian tissues back into women and that ovulation can occur as a result. However, so far no resulting pregnancies have been reported in humans.
Mr Hreinsson said: "We hope to be able to transplant the cryopreserved tissue for these patients within the next decade. The results of this study so far encourage us to continue with our research."
The study also enables the researchers to start to understand how and when follicles in Turner's syndrome girls start to disappear. He said: "Our results give us a model to understand follicular atresia and we now have more information about the time frame in which the follicles disappear. The mechanisms involved remain to be elucidated."
Abstract no: O-191
1 The laparoscopies were uneventful and without any severe after-effects. The patients came to the hospital in the afternoon of the day before the operation for preparations, and then went home again. The operation was performed under general anaesthetic the next morning, and in most cases the girls were able to go home in the afternoon. The hospital tried to do the operations on a Friday so that the girls could rest over the weekend, thereby missing the minimum amount of school.
2 At puberty a girl would normally have between 250,000 and 400,000 follicles in her ovary.
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