Sperm:Oocyte ratios in an in vitro fertilization (IVF) program
During the past few years, many oocyte insemination techniques, including microinjection, have evolved in the treatment of male-factor infertility. This preliminary study was designed to evaluate whether microdroplet insemination could be considered a reliable technique, especially for semen samples with male-factor defects. The first objective was to assess fertilization rates obtained by inseminating sibling oocytes using both the conventional IVF and the microdroplet method (Group 1). The second objective was to evaluate subsequent embryo development and pregnancy rates resulting from microdroplet insemination, in addition to formulating adequate sperm∶ oocyte ratios for various semen categories (Group 2). Four semen categories were studied including fresh normal sperm, frozen/thawed normal sperm, and male-factor sperm with one defect and two or three defects.
Group 1 consisted of 54 couples; no statistical significance was found in the fertilization rates between test tube and microdroplet insemination in all four semen categories. Based on these results, patients from Group 2 (48 couples) had their oocytes inseminated only in microdroplets with sperm:oocyte ratios ranging from 2000 to 10,000 motile sperm:1 oocyte. The average fertilization rate for male-factor sperm was 55%, with a 91% cleavage rate.
Higher fertilization rates were observed in the lowest range of sperm∶oocyte ratios (2000–4000∶1) for male-factor sperm with one defect and in the highest range (8000–10,000∶1) for male-factor sperm with two or three defects. Polyspermy occurred in only 0.4% of the oocytes inseminated. Microdroplet insemination is an alternative treatment for moderate to moderately severe male-factor infertility, establishing a bridge between conventional IVF and microinjection. With adequate sperm∶oocyte ratios, this technique allows the natural selection process of fertilization in vitro to take place, without the high incidence of polyspermy or mechanical damage frequently observed in assisted fertilization techniques.
Key wordsmicrodroplet insemination sperm:oocyte ratios male-factor infertility polyspermy natural barrier
Unable to display preview. Download preview PDF.
- 3.Trounson AO: The choice of the most appropriate microfertilization technique for human male factor infertility (submitted for publication), 1993Google Scholar
- 9.Whittingham DG: Culture of mouse ova. J Reprod Fertil (Suppl) 1971;14:7–21Google Scholar
- 10.World Health Organization: WHO Laboratory Manual for the Examination of Human Semen and Semen-Cervical Mucus Interaction. Cambridge, Cambridge University Press, 1992Google Scholar
- 19.Dale B: Fertilization in Animals. London, Institute of Biological Studies in Biology, Edward Arnold, 1983Google Scholar
- 20.Dale B: Fertilization.In Human Physiology from Cellular Mechanisms to Integration, R Greger, H Koepchen, W Mommaerts (eds). Springer Verlag, Heidelberg, 1993Google Scholar