Lens of the eye. False-colour scanning electron micrograph (SEM) of fibre-like cells that form the lens of the eye. Lens cells run diagonally (dark green) across this field of view. The transparency of the lens (width 4 millimetres) is due to the absence of nuclei in these cells, and to the crystalline precision of their arrangement. The zip-like rows of ball-and-socket joints (seen here) that bind these cells together may also play a part. The cells of the lens are called fibres because of their dimensions, with lengths of 10 millimetres and diameters of 5 micrometres. Magnification: x2900 at 6x7cm size. Magnification: x4500 at 4x5 inches size.