Coloured scanning electron micrograph (SEM) of pollen grains clustered to the stigma of the cocksfoot grass (Dactylis glomerata). Cocksfoot pollen, a summer wind-dispersed pollen, is a major cause of hay fever (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 (an allergen) causing the release of various 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: x70 at 35mm size. original is bw print B786/070