M. Muñoz

Timing of cell division in human cleavage-stage embryos is linked with blastocyst formation and quality.

Noninvasive markers of embryo quality are being sought to improve IVF success. The present study aimed to discover possible associations between embryo division kinetics in the cleavage stage, the subsequent ability of human embryos to reach the blastocyst stage and the resulting blastocyst morphology. A retrospective cohort study analysed 834 embryos from 165 oocyte donation couples using a time-lapse monitoring system that allowed the recording of the exact timings for key events related to embryo development. Timing parameters were categorized into four quartiles. The probability of an embryo developing to a blastocyst was linked to a strict chronology of development. To further evaluate the relationships between these morphokinetic parameters and subsequent blastocyst formation, the ensuing blastocyst morphology was compared with a viability score based on a hierarchical classification of the cleavage-stage morphokinetic parameters. It is concluded that the kinetics of early embryo development and the potential for human embryos to develop to the blastocyst stage on day 5 are closely related and that time-lapse-based evaluation of the exact timing of early events in embryo development is a promising tool for the prediction of blastocyst formation and quality according to the proposed model.

Looking for molecular biomarkers of cryodamage in donors semen

OBJECTIVE: Sperm cryopreservation is a widespread tool in assisted reproduction for the management of male infertility and it is mandatory for sperm donor programs. It is wellestablished that cryopreservation causes loss of sperm motility, impacting on its reproductive competence. Therefore, the selection of sperm donor samples with good freezability and fertilization abilities is important for optimization of sperm banks. The molecular basis of the vulnerability to cryopreservation is still unknown. Microarray provides a powerful tool to explore the molecular mechanisms involved in cryoinjury. The objective of this study is to characterize the gene expression profiles of semen samples according to their resistance to cryopreservation and to determine the impact of cryodamage on pregnancy outcomes after donor intrauterine insemination (IUI).

96 THE USE OF CRYOPRESERVED HUMAN BLASTOCYSTS (B) AFTER VITRIFICATION RESULTS IN OPTIMAL IMPLANTATION AND CLINICAL PREGNANCY RATES

development of vitrified bovine oocytes. Mechanisms of positive influence pre-treating bovine oocytes with the follicle fluid prior to vitrification on nuclear-cytoplasmic maturation of oocytes are under further investigation. The results propose that these markers (content of calcium in intracellular stores, level of mitochondrial activity and concentration of NADH) may be considered in further optimization of the conditions for vitrification of oocyte. This study was supported by grant No.10 04 00389-a from Russian Foundation of Basic Research.