Importance of the use of short and long sperm pre-incubation periods in assessing the fertilizing capacity of human spermatozoa by hamster test

: The fertilizing capacity of semen samples of seven fertile men was studied in vitro using zona-free hamster ova (hamster test). Spermatozoa of each sample were pre-incubated 4 or 24 h before ova were inseminated for 3 h. An extended insemination for an additional 3 h was also performed after the shorter pre-incubation. The overall ovum penetration rate changed from 0 to 100% (mean 52%) after short (4 h) sperm pre-incubation and from 10 to 100% (mean 55%) after long (24 h) pre-incubation. Taking into account the combination of short and long pre-incubation periods, all donors reached a penetration rate of 67 to 100%. The results indicate that both short and long pre-incubation periods must be employed when the hamster test is used diagnostically to assess the fertilizing capacity of human spermatozoa.