Fern (Pilularia sp.) sporocarp. Light micrograph of a section through a sporocarp from a pillwort fern, showing the spores inside. Sporocarps are specialised spore-producing structures within the sporophytes of ferns. This sporocarp consists of four chambers. Two containing microspores (brown dots) and two containing megaspores (large round). Microspores develop into male plants (gametophytes), whereas megaspores develop into female plants. Magnification: x13 when printed 10 centimetres wide.