Differential susceptibility of the embryo to inorganic lead during periimplantation in the mouse.

The effect of intravenously administered inorganic lead on periimplantation period of embryonic development in the mouse was investigated with light microscopy. Three developmental stages were studied: the attachment of the blastocyst, the invasion of the trophoblast and the formation of the primitive streak. All three stages were affected, but the stage of invasion was found to be the most susceptible to lead as determined by decrease in frequency of animals with normal embryos.