Light micrograph of a longitudinal section of a bronchus. The epithelium (dark violet at top) is ciliated and goblet cells, which secrete mucus, are occasionally found. It is supported by a thick layer of highly vascular connective tissue known as the lamina propria. This is separated from the submucosa by a layer of smooth muscle (pink and compact). The vacuolated sheath running from centre right to bottom left is a layer formed by hyaline cartilage. Magnification: x25 at 35mm size.