Testicular dysgenesis and endocrine disrupters
Niels E Skakkebaek
Several recent animal studies have revealed that the gonad is particularly sensitive to exposures to endocrine disrupters during the early fetal period, when sex differentiation occurs. Thus exposure to doses of phthalates, which have small or no effects when given to adult rats, can have pronounced effects in male offspring of pregnant rats exposed to the same doses of DEHP and DBP. At certain dose levels the effects include severe dysgenesis of the testis, undescended testis, low sperm count, subfertility and hypospadias. Several international research groups are these years focusing on the possibility that endocrine disrupters may be to blame for some cases of human adult male reproductive problems, including poor semen quality and testis cancer, which may share etiology with congenital malformations like hypospadias and undescended testis. We have suggested that such disorders sometimes may be due to a testicular dysgenesis syndrome (TDS). An important part of the research puzzle was the demonstration that the precursor-cells of testis of young adults with cancer are gonocyte-like and have stem cell characteristics.
A rapid increase in some of the mentioned reproductive abnormalities, e.g. testis cancer, lends support to the idea that environmental factors including lifestyle play a role. In several studies, we and others have seen associations between mothers exposures to endocrine disrupters and reproductive problems in their sons. The significance of the findings should be seen in light of the widespread occurrence of poor semen quality among young men and the high and increasing need for management of male infertility by the use of ICSI.