The protocol followed results in high rates of survival and potential for in-vitro maturation, but has a deleterious effect on the organization of the meiotic spindle of human oocytes cryopreserved at both the GV and MII stages.

We used fluorescent in situ hybridisation (FISH) to detect nine chromosomes (1,13,15,16,17,18,21,22 and X) in 89 first Polar Bodies (1PBs), from in vitro matured oocytes discarded from IVF cycles. In 54 1PBs, we also analysed the corresponding oocyte in metaphase II (MII) to confirm the results; the other 35 1PBs were analysed alone as when preimplantation genetic diagnosis using 1PB (PGD-1PB) is performed. The frequency of aneuploid oocytes found was 47.5%; if the risk of aneuploidy for 23 chromosomes is estimated, the percentage rises to 57.2%. Missing chromosomes or chromatids found in 1PBs of 1PB/MII doublets were confirmed by MII results in 74.2%, indicating that only 25.8% of them were artefactual. Abnormalities observed in 1PBs were 55.8% whole-chromosome alterations and 44.2% chromatid anomalies. We observed a balanced predivision of chromatids for all chromosomes analysed. Differences between balanced predivision in 1PB and MII were statistically significant (Po0.0001, v 2 test); the 1PB was most affected. The mean abnormal segregation frequency for each chromosome was 0.89% (range 0.52-1.70%); so, each of the 23 chromosomes of an oocyte has a risk of 0.89% to be involved in aneuploidy. No significant differences were observed regarding age, type of abnormality (chromosome or chromatid alterations) or frequency of aneuploidy. Nine of the 35 patients (25.7%) whose 1PB and MII were studied presented abnormalities (extra chromosomes) that probably originated in early oogenesis. Analysis of 1PBs to select euploid oocytes could help patients of advanced age undergoing in vitro fertilization (IVF) treatment.

Knowledge of the nature of embryo growth, and the handling and scoring of quality in human embryos are significant aspects for embryologists in IVF clinics. This review describes the formation, growth and maturation of human oocytes, many aspects of fertilization in vitro, embryonic transcription during preimplantation stages, and the formation of polarities, timing controls, role of mitochondria and functions of endocrine and paracrine systems. Modern concepts are fully discussed, together with their significance in the practice of IVF. This knowledge is essential for the correct clinical care of human embryos growing in vitro, especially in view of their uncharacteristic tendency to vary widely in implantation potential. Underlying causes of such variation have not been identified. Stringent tests must be enforced to ensure human embryos develop under optimal conditions, and are scored for quality using the most advanced techniques. Optimal methods of culture are described, including methods such as co-culture introduced to improve embryo quality but less important today. Detailed attention is given to quality as assessed from embryonic characteristics determined by timers, polarities, disturbed embryo growth and anomalous cell cycles. Methods for classification are described. Approaches to single embryo transfers are described, including the use of sequential media to produce high-quality blastocysts. These approaches, and others involved in surgical methods to remove fragments, transfer ooplasm or utilize newer approaches such as preimplantation diagnosis of chromosomal complements in embryos are covered. New outlooks in this field are summarized.

Nowadays, high-dose chemotherapy and radiotherapy treatments for cancer are more effective but can severely affect the ovarian follicular store, compromising the fertility of surviving young patients. A promising alternative to prevent fertility loss in these patients is the cryopreservation and transplantation of ovarian tissue. Slices of animal and human ovarian tissue have been shown to survive the cryopreservation process. After transplantation, follicular development and restoration of hormone secretion have been observed in animal and human studies. This review addresses recent developments on ovarian tissue transplantation in animals and humans. We also illustrate the indications and technical difficulties of the procedure and the ethical issues that should be considered.

Three cases of preimplantation genetic diagnosis (PGD) (two for sexing and one for aneuploidy screening) are presented. Embryo biopsy was performed at day 3 and diagnosis was established with fluorescent in situ hybridization (FISH). Embryos not used for replacement were cultured in sequential media for blastocyst development. Blastocyst rate was 39.3 per cent. Confirmations of diagnosis were established with FISH in blastocysts and arrested embryos. Mosaicism was observed in 7/8 blastocysts (mean number of cells analysed: 55.5) and 5/8 arrested embryos. The percentage of abnormal cells was 17.1 per cent for blastocysts and 54 per cent for arrested embryos. Polypoid cells were observed in 4/8 blastocysts. Confirmation of diagnosis at the blastocyst stage is a useful tool in PGD.

Preimplantation genetic diagnosis (PGD) of first polar bodies (1PBs) has been used in carriers of balanced chromosomal reorganizations and also for aneuploidy screening. Although an acceptable number of normal or balanced embryos is usually obtained using PGD in translocation carriers, the pregnancy rate is disappointingly low. To determine whether aneuploidy of chromosomes not involved in the chromosome rearrangements could be the cause of the low pregnancy rates achieved, the present authors analysed the segregation products of three translocation carriers, t(8;13)(q24.1;q22) and two Robertsonian (Rob)(13;14), using 1PBs, and afterwards another eight chromosomes in the same 1PBs, for a total of 10 chromosomes in each 1PB, that is chromosomes 1, 8, 13, 14, 15, 16, 17, 18, 21, 22 and X. In the reciprocal translocation, chromosomes with different chromatids due to meiotic recombination were found. Only one out of nine 1PBs was normal for the reorganization products but no aneuploidies were found after PGD in this case. In the two balanced Rob(13;14), six out of 12 and four out of 11 1PBs were normal or balanced for the reorganization but only one oocyte was euploid for all the chromosomes analysed in each case; a single embryo transfer was made in both but no pregnancy was achieved. The incidence of aneuploidy for the chromosomes not involved in the Robertsonian translocations was extremely high (91.7% and 81.8%). Extra chromosomes were present in most of the aneuploid oocytes (81.8% and 90%). The reason for this increase could be the tendency to non-disjunction related to advanced maternal age combined with an interchromosomal effect resulting in the presence of synaptic errors in other chromosome pairs.

Implantation failure rates after in-vitro fertilization (IVF) can be reduced in the IVF laboratory using two different techniques: assisted hatching and embryo co-culture on monolayer feeder cells. A review of the different methodologies and the results gained using these techniques is reported. Preliminary results obtained in the Reproductive Medicine Service of the Institut Universitari Dexeus, Barcelona, Spain using these techniques are also presented.

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