Scots pine (Pinus sylvestris) ovule. Light micrograph of a section through an ovule from a female cone of a Scot's pine tree, showing the archegonium (purple-blue) with the ovuliferous scale and bract scale resting on top, and the megaspore wall (brown). Within every female pine cone, two ovules are produced side by side on the upper surface of each ovuliferous scale. Each ovule arises as a group of cells that forms a rounded hump of tissue called the nucellus (blue). Within each ovule is the archegonium, which produces the female gametes (ova, eggs, brown). Magnification: x3 when printed 10 centimetres wide.