Comparative effects of di(n-butyl) phthalate exposure on fetal germ cell development in the rat and in human fetal testis xenografts

Abstract

Background: Phthalate exposure induces germ cell effects in the fetal rat testis. Although experimental models have shown that the human fetal testis is insensitive to the steroidogenic efects of phthalates, the efects on germ cells have been less explored. Objectives: We sought to identify the efects of phthalate exposure on human fetal germ cells in a dynamic model and to establish whether the rat is an appropriate model for investigating such efects. Methods: We used immunohistochemistry, immunofluorescence, and quantitative real-time polymerase chain reaction to examine Sertoli and germ cell markers on rat testes and human fetal testis xenografts after exposure to vehicle or di(n-butyl) phthalate (DBP). Our study included analysis of germ cell diferentiation markers, proliferation markers, and cell adhesion proteins. results: In both rat and human fetal testes, DBP exposure induced similar germ cell effects, namely, germ cell loss (predominantly undiferentiated), induction of multinucleated gonocytes (MNGs), and aggregation of diferentiated germ cells, although the latter occurred rarely in the human testes. Te mechanism for germ cell aggregation and MNG induction appears to be loss of Sertoli cell–germ cell membrane adhesion, probably due to Sertoli cell microflament redistribution. conclusions: Our fndings provide the frst comparison of DBP efects on germ cell number, differentiation, and aggregation in human testis xenografts and in vivo in rats. We observed comparable efects on germ cells in both species, but the efects in the human were muted compared with those in the rat. Nevertheless, phthalate efects on germ cells have potential implications for the next generation, which merits further study. Our results indicate that the rat is a human-relevant model in which to explore the mechanisms for germ cell efects.