The semen of fertile men. II. Semen characteristics of 100 fertile men.

From a population of men applying for voluntary sterilization, 100 consecutive cases were selected according to the following criteria: (1) each man had fathered at least two children; (2) at the time of the request for a vasectomy the man's wife was pregnant; and (3) a complete prevasectomy semen analysis, including sperm morphology, was available. The usual parameters of human semen evaluation are reported: the mean volume of the ejaculates was 3.3 ml +/- 0.84 SD (range, 0.5 to 11 ml); the mean sperm density was 81 million/ml +/- 57 SD (range, 4 to 318); while the geometric mean, which according to the sample distribution is more representative, was 68. The mean percentage of motile sperm was 63% +/- 16 SD (range, 10 to 95%); the grade of forward progression was 3 +/- 0.55 SD (range, 2 to 4); and for sperm morphology the mean number of sperm with oval heads was 75% +/- 6 SD (range, 21 to 90%). Statistical comparison of these findings with those of our previous study of the semen of 1300 fertile men revealed complete agreement; minor statistical differences, on single parameters, with three similar studies are indicated. A positive relationship between the different variables, sperm density and sperm motility (in percentage of motile sperm and degree of forward motion), as well as between the two variables of sperm motility and sperm morphology to the other variables was confirmed.