Spermarche--the age of onset of sperm emission.

Gonad maturation in boys is not characterized by a critical visible event such as menarche in girls. Establishing spermatogenesis by masturbation in maturing boys may be considered inappropriate. In order to estimate the median age of spermarche, a group of 155 normal schoolboys were examined twice (ages 12 and 13 years) for the occurrence of sperm in the first voided morning urine. The boys were requested to bring a daily sample for 10 consecutive days. Over 90% brought at least two samples and 50% brought 5-10 samples. The rate of boys with spermaturia at each age was calculated by the life-table method to adjust for the varying number of samples. New spermaturia was detected with each additional sample in the boys who brought in a greater number of samples. The urine examination carried a considerable false negative rate; even in boys who brought five or more samples, over 40% of boys positive at age 12 were negative at age 13. The rate of spermaturia at age 12 years was 37.5%, and at age 13 it was 68.9%. Our previous report showed the rate at age 11 years to be less than 1%. Because of an uncertain number of false negatives, these are probably under estimates of the true rate of spermatogenesis. The occurrence of spermarche was significantly associated with maturation of secondary sex characteristics.