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Sperm DNA fragmentation (SDF) is implicated in male infertility and adverse reproductive outcomes. With the publication of many studies regarding the etiologies and contributors to SDF, as well as the effects of SDF, guidelines are necessary to aid clinicians in the application of SDF for male fertility evaluation. Two recent clinical practice guidelines were published by Agarwal et al and Esteves et al. In this article, we have evaluated and compared both guidelines. We have found fairly similar recommendations between the two guidelines and have also highlighted the differences between them. Finally, we have summarized and combined the best practice recommendations from both guidelines.

Vitrifi cation is an excellent tool in the IVF laboratory, enabling options and offering fl exibility in assisted reproduction. The technology of cryopreservation has been underway since the early 20 th century. The advent of vitrifi cation has advanced the expectations in routine clinical practice in the IVF laboratory presenting impressive results both in post-thaw survival, and in clinical pregnancy rates, as well as signifi cantly enhancing clinical results on preimplantation genetic diagnosis (PGD). Contradicting opinions have been published recently on the limitations and potential that vitrifi cation has in the laboratory, as well as on the optimal approach to employ vitrifi cation in IVF. This review aims to present a comprehensive analysis of the practical aspects of vitrifi cation including concerns and options regarding its use on oocytes and embryos while comparing it with the traditional "slow-freezing" cryopreservation technique. РЕЗЮМЕТехнология криоконсервации применяется с начала ХХ в. Открытие технологии витрификации повысило ожидания в области утвержденных клинических деятельностей в лабораториях по ин-витро фертилизации, привело к отличным результатам, как в отношении выживания после размораживания и количества беременностей, так и в отношении значительного улучшения клинических результатов преимплантационной генетической диагностики. В последнее время появились противоречивые утверждения относительно потенциала и ограничения применения витрификации в лабораторных условиях, а также относительно оптимального применения витрификации в области методик ин-витро фертилизации. Целью данной работы является предоставление подробного анализа практических сторон витрификации, в том числе и возможных рисков и вариантов её применения в отношении ооцитов и эмбрионов, по сравнению с традиционными методиками криоконсервации способом "медленного замораживания". В заключение можно сказать, что для лабораторий ин-витро фертилизации витрификация является отличным средством, которое предоставляет возможности выбора и гибкости в области искусственного оплодотворения.Ключeвые слова: ооцит, эмбрион, витрификация, криоконсервация, ин-витро фертилизация Folia Medica 2014; 56(3): 161-169

There is a great body of evidence suggesting that in both humans and animal models the microRNA-34/449 (miR-34/449) family plays a crucial role for normal testicular functionality as well as for successful spermatogenesis, regulating spermatozoa maturation and functionality. This review and critical analysis aims to summarize the potential mechanisms via which miR-34/449 dysregulation could lead to male infertility. Existing data indicate that miR-34/449 family members regulate ciliogenesis in the efferent ductules epithelium. Upon miR-34/449 dysregulation, ciliogenesis in the efferent ductules is significantly impaired, leading to sperm aggregation and agglutination as well as to defective reabsorption of the seminiferous tubular fluids. These events in turn cause obstruction of the efferent ductules and thus accumulation of the tubular fluids resulting to high hydrostatic pressure into the testis. High hydrostatic pressure progressively leads to testicular dysfunction as well as to spermatogenic failure and finally to male infertility, which could range from severe oligoasthenozoospermia to azoospermia. In addition, miR-34/449 family members act as significant regulators of spermatogenesis with an essential role in controlling expression patterns of several spermatogenesis-related proteins. It is demonstrated that these microRNAs are meiotic specific microRNAs as their expression is relatively higher at the initiation of meiotic divisions during spermatogenesis. Moreover, data indicate that these molecules are essential for proper formation as well as for proper function of spermatozoa per se. MicroRNA-34/449 family seems to exert significant anti-oxidant and anti-apoptotic properties and thus contribute to testicular homeostatic regulation. Considering the clinical significance of these microRNAs, data indicate that the altered expression of the miR-34/449 family members is strongly associated with several aspects of male infertility. Most importantly, miR-34/449 levels in spermatozoa, in testicular tissues as well as in seminal plasma seem to be directly associated with severity of male infertility, indicating that these microRNAs could serve as potential sensitive biomarkers for an accurate individualized differential diagnosis, as well as for the assessment of the severity of male factor infertility. In conclusion, dysregulation of miR-34/449 family detrimentally affects male reproductive potential, impairing both testicular functionality as well as spermatogenesis. Future studies are needed to verify these conclusions.