The relationship between acridine orange fluorescence of sperm nuclei and the fertilizing ability of human sperm

Objective: To determine whether the outcome of IVF can be predicted by acridine orange (AO) nuclear fluorescence of sperm. Design: Based on the fact that AO nuclear fluorescence color after acid treatment reflects maturity (green fluorescence) or immaturity (yellow to red fluorescence) of spermatozoa, the relationships between sperm maturity and the outcome of IVF, subzonal insemination, or intracytoplasmic sperm injection (ICSI) were investigated. Setting: The NF program at the Obstetrics and Gynecology Hospital, Fukushima Medical College. Patients: Sixty-eight patients undergoing 68 IVF treatment cycles. Main Outcome Measures: Acridine orange fluorescence of sperm nuclei and successful oocyte fertilization. Results: Conventional semen parameters (sperm concentration and percentages of motile or morphologically normal spermatozoa in semen) did not correlate with the incidence of spermatozoa with green AO fluorescent (mature) nuclei. When greater than or equal to 50% of spermatozoa in semen samples exhibited green AO nuclear fluorescence, IVF was always successful. When green AO nuclear fluorescence was <50%, only 39% of IVF treatment cycles (13/33) were successful. Only green AO fluorescent spermatozoa were able to bind efficiently human zona pellucida. When the incidence of green AO fluorescent spermatozoa was <50%, no pregnancy resulted even though an average of 26% of the oocytes could be fertilized by ICSI. Conclusion: The spermatozoa which fertilized oocytes in vivo and in IVF were limited to those whose nuclei exhibited green AO fluorescence. Intracytoplasmic sperm injection may be the method of choice when the incidence of green AO nuclear fluorescence is low regardless of the results of semen analysis.