Figure 3.

Cumulative number of patients for the percentage of acrosome‐reacted spermatozoa after induction by means of the low‐temperature method of 76 patients (a), and of the acrosin activity index measured by means of the gelatinolysis technique (b) of 110 patients. Patients with a fertilization rate higher than 50% show a normal distribution while those who show poor fertilization (fertilization rate < 50%) are left‐shifted. Arrows indicate the cut‐off points of the tests. Patients with a normal acrosome reaction and normal acrosin activity index, but low fertilization probably have fertilization disorders other than decreased acrosome reaction or acrosin activity. Therefore, only in those cases where the specific test, acrosome reaction or acrosin activity, is abnormally low, male infertility can be attributed to that particular sperm function. For patients where these functional tests were normal, the fertility status has therefore to be regarded as unknown. (▪) Fertilization rate < 50%, (□) fertilization rate > 50%.