Structure of the normal rat larynx.

Recent studies have shown the rat larynx to be an important organ in the evaluation of irritancy of inhaled materials. Serial sections and scanning electron microscope observations have clarified its basic structure. In particular the cartilage pattern and the distribution of the epithelia lining the lumen have been determined. There are 2 specialised epithelia--stratified squamous (found in areas subject to wear) and ciliated pseudostratified columnar (which produces and transports mucus). Aways intervening between these is an unspecialised epithelium, the non-ciliated columnar. The marked variation in type of epithelium over a short distance within the larynx emphasises the need to take sections in the same plane when comparing different specimens.