Skin. Comparison between a scanning election micrograph (SEM left) and transmission electron micrograph (TEM right) of keratinocyte skin cells, which are found in the epidermis layer of the skin. The cells have a large nucleus (blue), which contains their genetic information. In the TEM image the cells' cytoplasm is rich in filaments of the protein cytokeratin (dark brown). The filaments extend into junctions between the cells known as desmosomes, which help the cells to withstand mechanical stress. Magnification: x4000 when printed 10 centimetres high. . For a series of comparisons between SEMs and TEMs see images C047/7006 to C047/7034.