**18. Conclusion**

Significant advances have been made in achieving fertilization, pregnancy and live birth in cases with severe male factor infertility, oocyte activation failure and ICSI technique. Usually fertilization is 80-100 percent in mature eggs, however, low or no fertilization can still occur. Most cases of no fertilization occur due to very low number of mature oocytes, failure of oocyte activation or non-availability of appropriate sperm. Repeated ICSI attempts results in fertilization in 85% of cases.
