A retrospective analysis of our in-vitro fertilization (IVF) and oocyte donation programmes was carried out in order to gain clinical knowledge of the factors involved in the aetiology of the endometriosis-associated infertility. Comparison between the IVF outcomes from 96 cycles in 78 patients with tubal infertility and from 96 cycles in 59 women with endometriosis indicates that endometriosis patients have a poor IVF outcome in terms of reduced pregnancy rate per cycle (P < 0.0004), reduced pregnancy rate per transfer (P < 0.002), and reduced implantation rate (P < 0.003). The analysis of patients undergoing oocyte donation for different reasons, including low response with or without endometriosis, showed that patients with this disease have the same chances of implantation and pregnancy as other recipients when the oocytes came from donors without known endometriosis. However, when the results of oocyte donation were classified according to the origin of the oocytes donated, patients who received embryos derived from endometriotic ovaries showed a significantly (P < 0.05) reduced implantation rate as compared to the remaining groups. Taken together, all these observations suggest that infertility in endometriosis patients may be related to alterations within the oocyte, which in turn result in embryos with decreased ability to implant.
Preimplantation diagnosis of the delta F508 deletion causing cystic fibrosis is possible through in vitro fertilization, biopsy of a cleavage-stage embryo, and amplification of DNA from single embryonic cells. This approach should be equally applicable to other single-gene diseases in which the defect has been identified. Analysis of a series of pregnancies, however, will be required to assess the method adequately.
This bioessay aims to explain the different effects of maternal ageing and postovulatory oocyte ageing on mammalian oocytes/embryos under the scope of 'the oxygen radical-mitochondrial injury hypothesis of ageing'. This hypothesis assumes a key role in the senescent process of oxygen radical damage to mitochondrial DNA, proteins and lipids. It is proposed that a decrease in intracellular ATP concentrations and glutathione (GSH)/glutathione disulphide (GSSG) ratio together with a concomitant increase in cytosolic Ca2+ are major factors causing the observed detrimental effects of ageing on cytoskeletal fibres, fertilization and embryo development.
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