Light micrograph of the concha within the nasal passages. Centrally is the nasal septum and lateral pairs of cartilage (blue) covered with olfactory mucosa at its thickest extent, with the thinner mucosal surfaces serving as a so-called respiratory epithelium. The latter acts to humidify, purify and adjust the temperate of inspired air. At the top is the brain and at the bottom are parts of the teeth in the oral cavity. Paraffin section, haematoxylin-eosin/alcian blue stain. Magnification: x 30 when width printed at 10cm.