fHDF/TER166 cells are derived from foreskin, whereas HDF/TERT164 cells are from adult skin (Cutis Laxa). Both cell lines show typical markers and characteristics of fibroblastoid cells and a stable growth rate. However, fHDF/TERT166 cells show a higher growth rate (population doubling time of 48 hours) compared to HDF/TERT164 cells (population doubling time of 60-72 hours).