False Colour Gallery

Leaf pores, SEM

Leaf pores. Coloured scanning electron micrograph (SEM) of stomata (holes) on the surface of a leaf. These structures perform a similar function to the pores in human skin, allowing water to pass out of the leaf. They also act like lungs, allowing carbon dioxide and oxygen (found in air) to pass into and out of the leaf. The stomata can be opened and closed depending on the conditions and the need to retain water. Water and carbon dioxide are combined in photosynthesis to produce sugars (transported around the plant in veins, one seen, brown) and oxygen (released via the stoma). This is a coriander plant leaf (Coriandrum sativum). Magnification: x465 when printed 10cm wide

© STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

Pine tree stem, light micrograph

Pine tree stem. Coloured light micrograph of a cross-section through the stem of a pine tree. (Pinus sp.). The red wood (xylem, lower left) has resin canals in it, which are outlined in green. The resin produced by the canals contains turpentine, which stops bacteria, fungi and insects from decomposing or eating the stems or leaves. Several growth rings are also distinguishable in the xylem, which can be counted to calculate the tree's age, as the cambium (thin green ring at the edge) forms one ring each year as it expands outwards. The green feature spanning these rings is the phloem, which transports nutrients around the plant. The darker region at top is the cortex, the outer portion of the stem. Magnification: x18 when printed 10cm wide

© STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

Stem cells, SEM

Stem cells, coloured scanning electron micrograph (SEM). Stem cells can differentiate into any other cell type. There are three main types of mammalian stem cell: embryonic stem cells, derived from blastocysts; adult stem cells, which are found in some adult tissues; and cord blood stem cells, which are found in the umbilical cord. The cells seen here are destined to become blood cells. During blood cell development in adults, stem cells develop through a process known as haemopoiesis. Blood cells have short lifespans and are therefore constantly produced by the bone marrow

© SCIENCE PHOTO LIBRARY