Nonlinear Microscopy of Eumelanin and Pheomelanin with Subcellular Resolution

Pump-probe microscopy nondestructively differentiates eumelanin and pheomelanin and can be used to quantify melanin distributions in thin biopsy slices. Here we have extended that work for imaging eumelanin and pheomelanin distributions on a subcellular scale, allowing elucidation of characteristics of different cell types. The results show that melanin heterogeneity, previously found to be characteristic of melanomas, persists on the subcellular scale. We have also found spectral changes associated with melanin located in melanophages that could potentially differentiate invasive pigmented melanocytes from melanophages without immunohistochemical staining.