Transfer of tritium-labeled vitamin D3 and 25-hydroxyvitamin D3 in ovine placenta

Placental transmission of IV-administered label from vitamin D3 and 25-hydroxycholecalciferol was studied in gestating ewes. Radioactivity concentrations were higher in the tissues of ewes dosed with vitamin D3 than in those dosed with 25-hydroxycholecalciferol. Concentrations were higher in maternal tissues than in fetal tissues. The highest radioactivity concentrations were found in kidneys, followed by concentrations in the adrenal glands.