bild

False-colour scanning electron micrograph (SEM) of pollen grains clustered to the stigma of the cocksfoot grass, Dactylis glomerata. Cocksfoot pollen, a summer grass pollen dispersed by the wind, is a major cause of hay fever (medical name Allergic rhinitis & pollenosis). Hay fever sufferers produce a sensitising antibody, immunoglobin E (IgE), which attaches to the surface of cells in the nose & eyes. It reacts with inhaled pollen causing the release of chemicals including histamine. Histamine causes the mucous membranes of the nose, eyes & throat to swell & become inflamed, bringing on the symptoms of hay fever. Magnification: x20 at 6x4.5cm size. (KEYSTONE/SCIENCE PHOTO LIBRARY/DR JEREMY BURGESS)