Figure 4 .

HPTLC of ceramides extracted from a 3-dimensional human skin model treated with sphingoids. Two wells containing 3-dimensional human skin model samples were pooled per sample. The weight of the keratinocyte layer was measured soon after the removal of this layer from the model; the values for all samples were subsequently adjusted to this weight. The same amount of lipids extracted from the keratinocyte layer of all samples was loaded onto the HPTLC plate. To visualize the ceramides, the HPTLC plate was treated with acetate/H₂PO₄/H₃PO₄/0.5% CuSO₄ solution and heated. Abbreviations of Cer I to VII represent Ceramide I to VII, these are classical names base on rate of flow in TLC. Recent names based on the structure, the combination of fatty acid and sphingoids, were shown in the parenthesis. A = α-hydroxy fatty acid, EO = Esterified ω-hydroxy fatty acid, N = Non-hydroxy fatty acid, P = Phytosphingosine, S = Sphingosine, H = 6-Hydroxy sphingosine.