Gecko eye lens. Coloured scanning electron micrograph (SEM) of a freeze fractured lens (crystalline lens) from a gecko's eye. The cells are in a stacked linear, fibre-like arrangement. A cell nucleus is seen at centre (blue). Its presence shows that these are immature lens cells, as mature cells have no nuclei or cell organelles. Magnification: x2200 when printed at 10 centimetres wide.