pleural mesothelial cell

Mesothelial cells are 1-4-μM thick and form a surface monolayer that is connected by both tight and gap junctions and by desmosomes. Mesothelial cells vary in shape from squamous to cuboidal, depending on both their location and the elastic properties of the lung and chest wall during ventilation.

The surface of the mesothelial cell exhibits elongate branching microvilli that express a surface glycocalix rich in hyaluronic acid.

The large surface area of the microvilli is adapted to facilitate fluid absorption. The mesothelial cell body shows an extensive network of actin and vimentin microfilaments.

Four major mesothelial keratins have been demonstrated, including a 40-, 44-, 52-, and 55-kDa species, along with a minor 46-kDa keratin.

The basal turnover of mesothelial cells is normally low, and it is rare to observe mitotic figures in the absence of inflammation. The source of mesothelial cell renewal appears to be a pluripotential submesothelial precursor cell that can either migrate to the pleural surface and contribute to the surface mesothelial lining, or give rise to subserosal spindle cells of the pleural mesenchyme.