Ultrastructure of the stroma of nasal polyps: cilia in stromal fibroblasts.

Ultrastructural examination of the stroma of simple nasal polyps was shown that there is an edematous framework of fibroblasts with abundant interdigitating cytoplasmic processes, a plexus of inflamed blood vessels, and a mixed infiltrate of active inflammatory cells. Solitary cilia were seen to arise from the stromal mesenchymal cells; no mycoplasma or viral inclusions were present. These features may have a relationship to the pathogenesis of nasal polyps. An immunologically induced liberation of vasoactive amines from mast cells results in increased capillary permeability and a consequent excess of intracellular fluid; the stromal cells attempt to check this expansion by an increase in collagen synthesis.