Stereological methods for quantifying cell surface specializations in epithelia, including a concept for counting desmosomes and hemidesmosomes.

We present stereological procedures for morphometric evaluation of intercellular junctions appearing in ultrathin sections of epithelia. A model representing desmosomes and hemidesmosomes as flat, circular discs differentiated within the plasma membrane of epithelial cells forms a basis for estimating number per unit volume of tissue or per unit area of cell surface. Methods for estimating relative surfaces are also provided. Consideration is given to problems of tissue sampling, varying feature size and finite section thickness. The procedures are improvements over earlier estimates of number per unit area of section or per unit length of membrane. Worked examples of calculations are included and methods are illustrated further by reference to quantitative studies of hamster cheek pouch epithelium during experimental carcinogenesis.