A method and apparatus for the in vitro determination and typification of well-differentiated or fully differentiated mammalian cells is disclosed. The method comprises placing a cell sample on a sampling device, irradiating the cells with infrared light, preparing an FT-IR spectrum from the absorption spectrum, calculating derivatives of the FT-IR spectrum and comparing the derivatives to reference FT-IR spectra for known cell types. The apparatus comprises an infrared source and measuring apparatus capable of recording an absorption spectrum, and software for measurement, evaluation, documentation, and derivation of the absorption spectra. Fourier transformation he method is particularly useful for typing cells from tissue biopsies in preparation for cell transplantation.