Fertility potential: a comparison of intra-abdominal and intracanalicular testes by age groups in children.

We compared a group of intra-abdominal (IA) with intracanalicular (IC) testes of the same age in order to see if there were differences in the fertility potential of the testes in these two locations. We also wished to determine at what age, if any, differences became apparent. Semithin (1 microm thick) sections of 54 IA and 103 IC testes between the ages of 3 months and 5 years were evaluated and the spermatic index (SI) calculated for each. The two groups were compared using mathematical models to describe the relationship between age and SI. Models of both IA and IC testes show a sharp decline in the SI during the first 1.8 years of life and remain near zero thereafter. The models are statistically indistinguishable, suggesting there is no detectable difference in the fertility potential of IA and IC testes up to 5 years. The SI appears to reach a critically low value in both groups between 8 and 9 months of age, suggesting that surgical intervention would be appropriate before this time.