OBJECTIVE: Conditio sine qua non to achieve ICSI fertilization is the presence of sperm viability. When complete absence of motility is encountered, the use of viability tests and phosphodiesterase inhibitors is necessary.DESIGN: Investigate whether kinetic patterns can be reinstated in immotile sperm cells that are resistant to motility enhancers.MATERIALS AND METHODS: Fresh or flash frozen sperm were assessed for motility. To mimic cases where all cells are immotile, highly motile sperm were demembranized utilizing 0.2% Triton-X, 30secs at room temp. Viability was evaluated before and after exposure to demembranization solution. Once demembranized, sperm were also exposed to 3μM of pentoxifylline. All immotile sperm were then reactivated by exposure to an ATP/MgSO4 (resuscitation) solution for 30sec and motility assessed on a 20μm dimpled slide. Kinetic patterns were defined as moving in place or twitching of the principal piece.RESULTS: A total of 5 consenting men (ave age 40.7 ± 7) donated their sample after a routine semen analysis with an average concentration of 49.6 ± 14x106/ml, motility of 54.7 ± 15%, and 4.7 ± 1% normal morphology. While 73.5% of all spermatozoa were viable, after demembranization they were rendered immotile, resilient to motility enhancer and with a viability of 0%. Upon exposure to the resuscitation medium, 63.7% (149/234) were revived as determined by flagellar twitching. Flash freezing without cryoprotectant to simulate loss of motility following cryopreservation displayed 0% viability and failed to be revived with a protease inhibitor. However, ATP treatment was able to restore kinetic patterns in 74.5% (284/381) of them.CONCLUSION: For men that had complete asthenospermia in their specimen or with compromised motility undergoing cryopreservation, spermatozoa may be resuscitated to identify those useful for injection. In spite of sperm membrane damage, kinetic mechanism is preserved provided that an adequate energy source is supplied. OBJECTIVE: Conditio sine qua non to achieve ICSI fertilization is the presence of sperm viability. When complete absence of motility is encountered, the use of viability tests and phosphodiesterase inhibitors is necessary. DESIGN: Investigate whether kinetic patterns can be reinstated in immotile sperm cells that are resistant to motility enhancers. MATERIALS AND METHODS: Fresh or flash frozen sperm were assessed for motility. To mimic cases where all cells are immotile, highly motile sperm were demembranized utilizing 0.2% Triton-X, 30secs at room temp. Viability was evaluated before and after exposure to demembranization solution. Once demembranized, sperm were also exposed to 3μM of pentoxifylline. All immotile sperm were then reactivated by exposure to an ATP/MgSO4 (resuscitation) solution for 30sec and motility assessed on a 20μm dimpled slide. Kinetic patterns were defined as moving in place or twitching of the principal piece. RESULTS: A total of 5 consenting men (ave age 40.7 ± 7) donated their sample after a routine semen analysis with an average concentration of 49.6 ± 14x106/ml, motility of 54.7 ± 15%, and 4.7 ± 1% normal morphology. While 73.5% of all spermatozoa were viable, after demembranization they were rendered immotile, resilient to motility enhancer and with a viability of 0%. Upon exposure to the resuscitation medium, 63.7% (149/234) were revived as determined by flagellar twitching. Flash freezing without cryoprotectant to simulate loss of motility following cryopreservation displayed 0% viability and failed to be revived with a protease inhibitor. However, ATP treatment was able to restore kinetic patterns in 74.5% (284/381) of them. CONCLUSION: For men that had complete asthenospermia in their specimen or with compromised motility undergoing cryopreservation, spermatozoa may be resuscitated to identify those useful for injection. In spite of sperm membrane damage, kinetic mechanism is preserved provided that an adequate energy source is supplied.