Immunohistochemical localization of metallothionein in cell nucleus and cytoplasm of fetal human liver and kidney and its changes during development

The distribution of metallothionein (MT) during human development was investigated using both immunohistochemical and biochemical methods. The level of MT in the fetal liver was higher than the adult liver levels. Higher levels of zinc (Zn) and copper (Cu) were also detected in the fetal liver compared to the adult liver. Although cadmium (Cd) was present in detectable levels in the human adult liver, none was detected in the human fetal liver. MT was localized in the nucleus and the cytoplasm of human fetal and neonatal hepatocytes, using a specific rabbit antibody raised to rat liver MT. In the adult human liver cells, MT was localized mainly in the cytoplasm. In the fetal and neonatal human kidney, MT was localized mainly in the nucleus and the cytoplasm of the proximal tubular epithelial cells. In the adult kidney, in addition to nuclear-cytoplasmic localization of MT, intraluminal localization was also observed.