False colour scanning electron micrograph (SEM) of pollen grains from the common oak flower Quercus robur. Oak trees flower in May/June producing copious quantities of pollen, which is dispersed by the wind. Oak pollen is a major cause of hay fever (medical term Allergic rhinitis & pollenosis). Sufferers produce an antibody, immunoglobin E (IgE), which attaches to cells in the nose & eyes. It reacts with inhaled pollen 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 hay fever attack. Magnification: X 170 at 35mm size. original is bw print B786/90