In vitro effects of cadmium chloride on preimplantation rat embryos

Preimplantation rat embryos (8-cell, morulae, blastocysts) were incubated for 24 hr in vitro in a Brinster medium with or without cadmium chloride (1 microgram/ml). CdCl2 arrested the development of both the 8-cell and morulae into blastocysts. Morphologic observations revealed the 8-cell embryo to have shrunken cells and pyknotic nuclei. Morulae appeared smaller in size with fewer cells than comparable controls. CdCl2 was clearly cytotoxic to the early blastocysts, inner mass cells were most damaged with cell death, pyknosis, and accumulation of debris.