A review of the morphology of human nasal mast cells as studied by light and electron microscopy.

This review discusses the distribution and classification of human nasal mast cells after the use of different fixatives, and some of their staining characteristics, both at the light- and electron-microscopical level. The problems encountered with alcoholic and formaldehyde fixation are discussed as well as the limitations of different stains (including the basic aniline dyes), esterase cytochemistry and immunological techniques. Also, the respective limitations of light and electron microscopy are compared. Cells studied by means of electron microscopy are much more difficult to quantify objectively. It is concluded that classification of mast cells--by means of their morphology, fixation and staining characteristics--into two categories (mucosal vs. connective tissue; T-vs. T/C cells) is simplistic, especially since human nasal mast cells are both heterogeneous and pleomorphic.