Phthalates impair germ cell development in the human fetal testis in vitro without change in testosterone production

Several studies have described an increasing frequency of male reproductive disorders, which may have a common origin in fetal life and which are hypothesized to be caused by endocrine disruptors. Phthalate esters represent a class of environmental endocrine-active chemicals known to disrupt development of the male reproductive tract by decreasing testosterone production in the fetal rat.

Using the organ culture system we developed previously, we investigated the effects on the development of human fetal testis of one phthalate--mono-2-ethylhexyl phthalate (MEHP)--an industrial chemical found in many products, which has been incriminated as a disruptor of male reproductive function.

Human fetal testes were recovered during the first trimester (7-12 weeks) of gestation, a critical period for testicular differentiation, and cultured for 3 days with or without MEHP in basal conditions or stimulated with luteinizing hormone (LH).

Whatever the dose, MEHP treatment had no effect on basal or LH-stimulated testosterone produced by the human fetal testis in vitro, although testosterone production can be modulated in our culture system. MEHP (10(-4) M) did not affect proliferation or apoptosis of Sertoli cells, but it reduced the mRNA expression of anti-Müllerian hormone. MEHP (10(-4) M) reduced the number of germ cells by increasing their apoptosis, measured by the detection of caspase-3-positive germ cells, without modification of their proliferation.

This is the first experimental demonstration that phthalates alter the development of the germ cell lineage in humans. However, in contrast to results observed in the rat, phthalates did not affect steroidogenesis.