Effect of inorganic lead on the mouse blastocyst in vitro.

In vitro culture of mouse blastocysts over the implantation period was used (1) to find out whether embryos recovered from uteri of mice given an injection of lead, which has been shown in a previous study to inhibit implantation in vivo, were capable of attachment and outgrowth when transferred to a lead free culture medium; (2) to study the effect of different amounts of inorganic lead in the culture medium on blastocyst viability and ability to attach and grow out. The levels of lead used in the medium were comparable to those found in uterine tissue of animals given an implantation inhibiting dose of lead. It was found that the preimplantation blastocyst was unaffected by the administration of lead to the mother as regards the ability to attach and grow out. It was also shown that normal blastocysts were adversely affected by the presence of lead in the culture medium. Addition of increasing amounts of inorganic lead (5, 10 and 20 mumol/l) caused a corresponding decrease in the ability of the blastocysts to attach and grow out, the highest concentration also causing abnormal appearance of the embryos within 48 hours of culture.