Estimating the testis volume during the fetal period using the stereological method.

The purpose of the present study is to assess the development of seminiferous tubule volume, stromal volume and total testis volume in the human fetal testis during the fetal period using the stereological method. In this study, we examined 90 testes of 45 human fetuses with no congenital anomalies and pathologies. They were aged between 12 and 40 weeks and localized between the scrotum and the abdomen. Total testis volume, seminiferous tubule volume, and stromal volume were estimated using Cavalier Principles. The weight and density of the testes were calculated as well. During the fetal period, the testes were firstly found on the right in the 27th week and on the left in the 32nd week in the scrotum. At the end of the third trimester and full term, the migration of the testes into scrotum was completed (98%). When the second trimester, third trimester and full term fetuses were compared, the differences between testis volumes were significant (p<0.001). The density of the testes between the groups was not significant (p>0.05). Testis parameters during the fetal period were not significantly (p>0.05) different between the right and left testes localization. The correlation between the fetal testis parameters was significant (p<0.001). Towards the end of the fetal period, the rate of seminiferous tubule volume to stromal volume changed in the favor of seminiferous tubule volume. It was observed that interstitial tissue became more regular and had a good organized structure with the progress of gestational age. In the third trimester, the lumen in the seminiferous tubules became more regular and clear and the interstitial tissue had a clear appearance.