Foetal eye. Light micrograph of a section through an eye from a developing foetus. From left to right, this view shows fused eyelids, the cornea, part of the iris, the developing lens (rounded area left of centre), the retina (upper and lower centre), and the optic nerve (elongated structure extending out to the right). The developing lens has a surface population of cells that progressively multiply and elongate into long lens fibres that make up the substance of the lens. Magnification: x133 when printed at 10 centimetres across.