Skin cell. Coloured transmission electron micrograph (TEM) of a section through a keratinocyte skin cell, which is found in the epidermis layer of the skin. At centre is the cell's large nucleus, which contains its genetic information. The cell's cytoplasm is rich in filaments of the protein cytokeratin (brown). The filaments extend into junctions between the cells known as desmosomes, which help the cells to withstand mechanical stress.