Permeability of the Syrian hamster placenta to manganous ions during early embryogenesis

Detectable amounts of radioactivity in embryonic tissues 24 and 96 hr after administration of the ion on day of pregnancy indicate that ⁵⁴Mn⁺⁺ crosses the placental barrier. All of the maternal tissues examined showed uptake of radioactivity. The levels of ⁵⁴Mn⁺⁺ decreased in both embryonic and maternal tissues between Day 9 and Day 12. All decreases were statistically significant.