Aspergillus niger fungus, coloured scanning electron micrograph (SEM). This is a fruiting body, or conidiophore. It is made up of chains of conidia, or spores, the reproductive cells of the fungus. Inhalation of A. niger's spores by individuals with a weakened respiratory system can cause an allergic reaction known as aspergillosis. Magnification x900 when printed at 10 centimetres wide.