Since its inception, ICSI has become the most widely used ART technique, and the ultimate treatment for severe male factor infertility. In this chapter, we provide fertilization and clinical pregnancy outcomes with ICSI utilizing oligo-, crypto- and astheno- zoospermic samples. We also describe the negative impact of ooplasmic dysmaturity on fertilization and propose methods to correct it. We also report the selection of spermatozoa with higher genomic integrity using a microfluidic chip in couples with high chromatin fragmentation and complete embryo aneuploidy. This will be followed by a discussion on the safety of ICSI in which we enlist various follow-up studies on the development and health of ICSI offspring through adulthood. To provide an overview on the widespread utilization of this procedure, we comment on the ICSI results reported worldwide.

Since the establishment of in vitro fertilization, it became quickly apparent that approximately half of the couples treated presented with a dysfunctional male gamete. To alleviate this issue, intracytoplasmic sperm injection (ICSI) was introduced to treat men with compromised semen parameters or azoospermia, and more recently high sperm chromatin fragmentation or sperm-linked oocyte activation deficiency. Because of its success, ICSI has been extended for cases with low egg yield, oocyte cryopreservation, and often for preimplantation genetic testing. Due to its versatility and reliability, ICSI has become the most popular ART and will be invaluable for emerging technologies such as in vitro gametogenesis and heritable genome editing. In this chapter, we discuss the development of ICSI, its current applications, and ongoing research that will contribute to the future of reproductive medicine.