Polarised light micrograph of common mallow (Malva sylvestris) pollen grains on a stigma. The grains have a spiked outer wall (exine), which may assist in their dispersal by improving their adherence to pollinating insects. Each pollen grain contains a male gamete (reproductive cell) that is intended to fertilise an egg or ovule (female gamete), and initiate the formation of a seed for a new plant. Stigmas are part of a plants female reproductive structure. Magnification: x140 when printed at 10 centimetres wide.