TESTICULAR MIGRATION: THE TRANSITION OF THE TESTES THROUGH THE INGUINAL CANAL. ANALISYS IN 208 HUMAN FETUSES
Objectives: During the human fetal period, the testes migrate from the abdomen to the scrotum, traversing the abdominal wall and the inguinal canal. Testicular migration happens in two distinct phases: the first phase corresponds to the testicular migration from the abdomen to the internal inguinal ring, and the second phase comprehends the transition of the testes through the inguinal canal until their definitive arrival at the scrotum. The objective of the present study is to analyze the testes’ transition through the inguinal canal during the human fetal period.
Material and Methods: We studied 208 human male fetuses ranging in age from 10 to 35 weeks post-conception (WPC). The gestational age of the fetuses was determined in WPC, according to the foot-length criterion. The fetuses were also evaluated regarding crown-rump length (CRL) and body weight immediately before dissection. The same observer analyzed the measurements. The fetuses were carefully dissected with the aid of a stereoscopic lens with 16/25X magnification. The abdomen and pelvis were opened to identify and expose the urogenital organs. Testicular position was classified as: a) Abdominal, when the testis was proximal to the internal ring; b) Inguinal, when it was found between the internal and external inguinal rings); and c) Scrotal, when it was inside the scrotum.
Results: Of the 416 testes, 315 (%) were abdominal, 49 (%) were inguinal and 52 (%) were scrotal. The 49 inguinal testes were observed in 29 fetuses ( %) aging between 17 and 29WPC, weighting between 203 and 1220g and with the CRL between 15 and 27.5cm. In 21 of the fetuses (%) with inguinal testes we observed the testes situated at the same time in the right and in the left canal and in 8 cases (%) we found asymmetry in testicular migration. All the fetuses with more than than 1650 g, 43cm of CRL and 30WPC had the testis in scrotum. We do not observe fetuses with less than 200g, 22.5cm of CRL and less than 17WPC with the testis in inguinal canal. The first case of inguinal testis was observed in a fetus with 17WPC, 203g and 15cm of CRL. The great majority (24 -%) of the 29 fetuses with inguinal testes aged between 20 and 26 WPC; two fetuses had 17WPC and 3 fetuses had more than 26WPC.
Conclusion: In this study we confirm that the transition of the testes through the inguinal canal is a fast process occurring between 20 and 26 WPC and in fetuses with more than 200g and 22.5cm of CRL
migração testicular, criptorquidia, testículo, fetos
UERJ - Rio de Janeiro - Brasil
tatiana silva costa gregory benzi, henrique barboza menezes, waldemar silva costa, francisco jose sampaio, luciano alves favorito