Distribution of radioactivity from 14C-formaldehyde in pregnant mice and their fetuses

The distribution of 14C after the administration of 14C-formaldehyde was studied in pregnant mice by a whole body low temperature autoradiographic technique. The concentrations of formaldehyde and its metabolites in maternal and fetal blood and tissues were determined in unsectioned tissues by liquid scintillation spectrophotometry. The binding of 14C from 14C-formaldehyde to cells and DNA in maternal and fetal mouse liver was also measured. Radioactivity of 14C deriving from 14C-formaldehyde was found immediately after injection, and showed strong accumulation and retention three hours after injection. The organs that had high concentrations at all studied survival intervals were maternal liver, intestinal mucosa, bone marrow, kidneys, and salivary glands. Considerable amounts of radioactivity were found in the fetuses at six hours after injection, and the concentrations were almost the same as in the maternal tissues. The elimination of 14C-formaldehyde and metabolites from the placenta and fetus occurred more slowly than from maternal tissue.