Histogenesis of mucin in follicular mucinosis. An electron microscopic study

Many dilated cystic ergastoplasms, including their granular, filamentous contents, the developed Golgi apparatuses, and vesicles were observed in the cytoplasm of affected root sheath cells, which were accompanied by much amorphous agglutination of fine granular or flocculent materials in the interstices. These extracellular substances were stained with ruthenium red and seemed to correspond to increased metachromatic materials, probably composed of hyaluronic acid. Possible structures for hyaluronic acid were discussed. Mucin in follicular mucinosis seemed to be produced by secretory function of follicle cells.