Electron microscopy and X-ray microanalyses of uterine epithelium from lead-injected mice in an experimental delay of implantation.

Mice in experimental delay of implantation were injected intravenously with 75 micrograms.g-1 body weight of lead chloride, corresponding to a dose of lead of about 56 micrograms.g-1 body weight. Delay of implantation was obtained by ovariectomy 3 days after mating followed by a depot dose of progesterone every fifth day. Electron microscopy showed that the uterine lumen, which was closed in control mice, was opened in lead-injected mice. This morphology suggested that lead caused an increase in uterine secretion. X-ray microanalysis of pyroantimonate precipitates in the uterine epithelium of injected mice demonstrated lead in the precipitates, suggesting that lead could have a direct effect on the function of the uterine epithelium and that lead also could be secreted into the uterine lumen and affect the blastocysts.