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 2001 S. Karger AG, Basel