False-colour scanning electron micrograph (SEM) of two pollen grains of cocksfoot grass, Dactylis glomerata, a major cause of hay fever (allergic rhinitis). The pit on the right-hand grain is the germination pore, out which the pollen tube grows. Cocksfoot pollen is a wind-dispersed summer pollen. Hay fever sufferers produce a sensitising 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 symptoms of hay fever. Magnification: x570 at 6x4.5cm size. JBU colouring: green & yellow. BW original is B786/073.