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 |