False-colour scanning electron micrograph (SEM) of a pollen grain from cocksfoot grass, Dactylis glomerata, a major cause of hay fever. The SEM shows a germinating pore from which a pollen tube emerges. Cocksfoot pollen is a summer grass whose pollen is dispersed by the wind. Hay fever suffer- ers produce a sensitising antibody, immunoglobin E (IgE), which attaches to 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, producing hay fever. Magnification: x330 at 35mm size, x830 at 6x6cm size.