ANALYSIS OF TESTICULAR MIGRATION DURING THE FETAL PERIOD IN HUMANS

Purpose: We present an analysis concerning the testicular migration an d its position correlated to body weight, crown-romp length and gestat ional age during the fetal period in humans without congenital abnorma lities. Materials and Methods: We studied bilaterally 142 testes taken from 71 fresh human fetuses between 10 and 35 weeks after conception. The fetuses were also evaluated in regard to crown-rump length and bo dy weight. The position of the testes was correlated to the fetal para meters. Results: In 37 fetuses (74 testes) at 10 to 23 weeks after con ception only 7 testes (9.45%) had migrated from the abdomen and were s ituated in the inguinal canal, in 19 fetuses (38 testes) at 24 to 26 w eeks after conception 22 testes (57.9%) had migrated from the abdomen and in 9 fetuses (18 testes) at 27 to 29 weeks after conception only 3 testes (16.7%) had not descended to the scrotum. The testes had not d escended into the scrotum in any fetus weighing 990 gm. or less and wi th a crown-rump length of 24.5 cm. or less. On the other hand, in all fetuses weighing more than 1,220 gm. and with a crown-rump length of m ore than 27.5 cm. the testis was in the scrotum. Conclusions: Until 23 weeks after conception the majority of testes remain in the abdomen. The more intense migration of the testes through the inguinal canal oc curred between 21 and 25 weeks after conception. After 30 weeks after conception all testes were descended to the scrotum in all fetuses.