The effect of teratogenic doses of trypan blue on the yolk sac placenta of the mouse. A histological and histochemical study

Injection of teratogenic doses of trypan blue into pregnant mice resulted in depression of acid phosphatase activity in embryonic visceral yolk sac endoderm. In addition, the apical localization of this enzyme was lost, and enzyme active loci were dispersed throughout the cytoplasm. Perinuclear Golgi structures were prominent in yolk sac cells of control mice incubated for thiamine pyrophosphatase activity. In trypan blue treated animals the Golgi apparatus was attenuated and disrupted. Whereas yolk sacs of most trypan blue treated embryos showed depression of acid phosphatase activity and morphological alteration in Golgi, only 25% of such embryos exhibited gross malformations. Trypan blue treatment may cause malformations by altering nutritive and transport functions of the yolk sac placenta or the dye may exert a direct effect upon the cells of the embryo.