41.0 MB (4.5 MB compressed)
4601 x 3118 pixels
38.9 x 26.4 cm ⏐ 15.3 x 10.4 in (300dpi)
DON FAWCETT / SCIENCE PHOTO LIBRARY DON FAWCETT / SCIENCE PHOTO LIBRARY
Immune system cells. Coloured Scanning Electron Micrograph (SEM) of a macrophage (blue) and two lymphocyte (yellow) cells of the human immune system. These cell types are both derived from white blood cells. The larger macrophage (or mono- cyte) often has an irregular shape. Macrophages engulf and digest foreign bodies; they wander across tissues to sites of infection and are the first immune response. Lymphocytes (T-cells or B- cells) are rounded and occur in the blood; they recognise foreign antigens and destroy invaders such as viruses and bacteria. Both cell types have thin projections on their surface called filopodia which are used for support and motility.
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