Immunohistochemical expression of S-100 protein in human embryonal fat cells

The aim of the present study was to investigate immunocytochemically the presence of S-100 protein in subcutaneous fat cells during early human embryogenesis (6-12 weeks of gestation). We found that preadipocytes in the subcutaneous tissue which were at different stages of differentiation were positive for S-100 protein. The other cells in the embryonal subcutis (mesenchymal cells differentiating into fibroblasts and fibrocytes and endothelial cells) showed a negative reaction for S-100. Our results imply that the S-100 protein is expressed from the beginning of lipidogenesis and possibly acts as a factor regulating lipid storage and body fat formation. It can be used as a reliable biochemical marker of human fat cell differentiation and for distinguishing them from the mesenchymal and the fibroblast cells in the human embryonal subcutis. Copyright (C) 2001 S. Karger AG, Basel.