A new method for evaluation of the acrosome reaction in viable human spermatozoa

Summary. The acrosome reaction of human spermatozoa was induced by changes of temperature. Spermatozoa were collected from fertile donors and a patient group, and selected by the “swim‐up” method. The spermatozoa were treated in two different ways: Protocol I: 24 hours at room temperature followed by additional incubation at 37 °C for 3 hours (control), and protocol II: 24 hours at 4 °C followed by additional incubation at 37 °C for 3 hours. The acrosome reaction of the viable spermatozoa was evaluated by a new method utilizing indirect immunofluorescence with anti‐outer acrosomal membrane antibodies and exposure to a hypo‐osmotic medium. In fertile donors as well as in the patient group, significant induction of the acrosome reaction (20%) was evident after exposure to low temperature (4°C). The spontaneous rate of acrosome reaction in the control group was below 7%.