[Distribution of lead in fetal rat tissue at different days of pregnancy]

In order to reveal the mechanism of the transplacental transfer of lead from mothers to fetus, tissues lead content of fetal rat at different days of pregnancy were determined and compared. Lead was administered to four groups of 4 week-old female Wistar rats for 50 days. The doses of lead were 0, 10, 50 and 200 mg/L in drinking water respectively. Rats were mated with non-lead-treated male rats. The pregnant rats in each group were then divided into four sub-groups by random. The pregnant rats in four sub-group of each group were sacrificed in turn at 10, 14, 17 and 20 days of gestation (dg). Blood lead of pregnant rats, lead burden of whole fetus, lead concentration of fetal brain, fetal liver and placenta were determined. Results indicated that lead concentration in fetal brain kept unchanged during the period of gestation, but lead content in whole fetus and fetal brain were increased with the days of gestation. But the lead concentration in fetus at 10 dg was higher than that at 14 dg. It seemed that higher lead absorption by the fetus was related to the newly emerged lead bonding-site in fetus, especially during the calcification of bones.