CYCLOSPORINE-INDUCED GINGIVAL HYPERPLASIA - AN ULTRASTRUCTURAL-STUDY OF THE ORAL EPITHELIAL PRICKLE CELLS

In this study the ultrastructural characteristics of the prickle cells of the human gingival epithelium after cyclosporin-A treatment are de scribed. The prickle cell layer shows hyperplasia, along with the well known hyperplasia of the connective tissue components. The prickle ce lls show large numbers of free ribosomes, rough endoplasmic reticulum profiles and well developed Golgi complexes. The intercellular space i s usually large and the neighboring cells are joined by desmosomes. In many cases the intercellular space is almost diminished and the cells are joined by a lot of desmosomes. Occasionally, a single cilium was observed to project into the intercellular space but the functional si gnificance of this observation is unknown. The tonofilaments exhibit a specific arrangement in the cytoplasm of the prickle cells and it is believed that they contribute to the formation of a 'tonofilament netw ork' which, along with the desmosomes, provide strength to the epithel ium. Possible mechanisms regarding the gingiva overgrowth are discusse d.