Squamous epithelium. Coloured transmission electron micrograph (TEM) of stratified squamous epithelial cells from the lining of the nasal cavity. This means there is more than one layer of cells and the superficial (top) layer are squamous cells, having an irregular, flattened shape ( not visible here). These are keratinised cells that provide a tough, impermeable barrier. The keratin filaments and desmosomes within the cells can be seen (blue), as can the nuclei. A basal dividing cell is seen at the bottom with the connective tissue lamina propria below. Magnification: x1300 when printed 10 centimetres wide.