Different skin cells from a human sample growing in a plate. In this photo you can find two types of cells that are crucial for the maintenance of skin: the smaller stem cells (or progenitors) and larger cells that are becoming specialised skin cell types. The larger red cells are the cells that have specialised and cannot divide anymore and located in the most external part of the skin. They are the ones that protects our body against mechanical forces, pathogens and dehydration for example. The smaller cells, are stem cells that are dividing our whole life forming the differentiated cells.