Skull anatomy by Leonardo da Vinci
Skull anatomy by Leonardo da Vinci. Historical artwork and notes on the anatomy of the human skull and teeth, by the Italian artist and scientist Leonardo da Vinci (1452-1519). This bisected skull shows the external structure (right), and dissected facial sinuses (left), the air-filled spaces inside the bones of the face. The diagram at lower left shows the teeth present in one half of the mouth: 4 incisors, 2 canines, 4 pre-molars, and 6 molars. Da Vinci was the first anatomist known to have correctly noted the number and root structure of human teeth. The notes are an example of his mirror writing, which was written backwards from right to left, and could be read in a mirror.
© SHEILA TERRY/SCIENCE PHOTO LIBRARY
Molar teeth, light micrograph
Molar teeth. Polarised light micrograph (PLM) of a section through molar teeth. These teeth, at the sides of the mouth, are used for grinding up and chewing food. They are capped with enamel (orange/pink, across top), the hardest substance in the body, which limits mechanical wear. Each tooth is anchored in the gum by two roots (dark vertical strips). These run down from the pulp cavities (solid purple areas), which contain a pulp of nerves and blood vessels. The pulp is surrounded by dentine (many colours), which forms the bulk of each tooth. Dentine is similar to, but harder than, bone. Magnification: x1.7 at 35mm size.
© Innerspace Imaging/Science Photo Library
Maize root, light micrograph
Maize root. Light micrograph of a section through the root of a maize plant (Zea mays) showing a vascular cylinder (centre). The cylinder is comprised of a central cluster of parenchyma cells (blue), surrounded by fused vascular bundles (black/green/blue) and the endodermis (black/red ring). The largest vessels seen here (white) are metaxylem, part of the xylem tissue in the vascular bundles. Xylem transports water and mineral nutrients from the roots throughout the plant, while phloem (light blue), the other component of the bundles, transports carbohydrates and plant hormones. Magnification: x44 when printed 10 centimetres wide.
© DR KEITH WHEELER/SCIENCE PHOTO LIBRARY