Differential analysis of the human anagen hair apparatus using lectin binding histochemistry

Cell differentiation in the human anagen hair apparatus was examined by lectin-binding histochemistry using seven different lectins: Con A, WGA, RCA-I, PNA, SBA, DBA and UEA-I. Con A and WGA positively stained almost all the cells in the hair apparatus. RCA-I and PNA positively stained the outer cells of the outer root sheath (ORS), but they did not stain the innermost cells (IMCs) of the ORS in the suprabulbar region. However, in the isthmus region, the IMCs showed positive staining with RCA-I, and more intense staining with PNA than that of the outer ORS cells. The ORS cells, including the IMCs, were negative with SBA and DBA below the suprabulbar region, whereas the IMCs became more strongly positive with these two lectins than the other ORS cells in the isthmus region. UEA-I strongly stained the IMCs, but not the outer ORS cells in the hair bulb. The latter cells became positive for UEA-I above the suprabulbar region. These findings indicate that the surface glycoconjugate distribution of the IMCs differs from that of the outer ORS cells. It is concluded that the IMCs of the ORS may undergo an independent cell differentiation process.