Novel method of selecting human spermatozoa for In Vitro fertilization
Traditionally, the diagnosis of male infertility is based on semen analysis when semen volume, sperm concentration, motility and morphology are evaluated. These characteristics help to assess how many spermatozoa are capable to get through the natural barriers of the female reproductive tract such as viscous cervical mucus, the uterus and into the fallopian tubes. The more spermatozoa are released into the vagina, and the more motile they are, the more spermatozoa will be able to penetrate through the cervical mucus and potentially find the oocyte. Even the morphology of spermatozoa provides information regarding the penetration ability and fertilization potential of sperm but cannot be an absolute indicator of fertility. Thus, these characteristics can help us to predict the chances of pregnancy in vivo and intrauterine insemination only, but have very limited clinical value in IVF and especially in ICSI when all natural barriers for sperm selection are eliminated. From a practical point of view sperm selection for IVF is one of the most important challenges, especially in ICSI, when the embryologist must manually and quickly choose a single spermatozoon and inject it into an oocyte. Therefore, an efficient technique for sperm selection can potentially improve fertilization and pregnancy rates in IVF. In this thesis I developed a novel physiological method of preparing and selecting spermatozoa for IVF/ICSI which is based on sperm penetration through viscous medium in vitro as a model of in vivo. The main hypothesis is that spermatozoa that are able to enter and progress through viscous medium in vitro have the best fertilization potential by analogy of spermatozoa that are able to penetrate through cervical mucus in female reproductive tract.
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