MIGRATION OF EPITHELIUM DURING PHENYTOIN-DEPENDENT GINGIVAL OVERGROWTH IN MICE

A small cavity was made in the mesiopalatal area of the maxillary firs t molar adjacent to the gingiva. Mice were maintained on 40 mg/kg phen ytoin (or on diluent for control) by daily intraperitoneal injections. After 9 weeks, light microscopic observations revealed that in experi mental mice, epithelial cells migrated towards the cavity and covered it. In controls, epithelial cell migration towards the cavity did not occur. For scanning electron microscopic (SEM) studies, specimens were fixed in 4% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2, for 2 h ours, dehydrated, critical point dried and coated with gold. The surfa ce of the outer gingival epithelium of experimental and of control mic e showed a honeycomb arrangement of the microridges suggesting their k eratinized nature. Epithelial cells lining the cavity showed well mark ed macroridges along their borders. Parallel microridges were observed on the upper surface of these cells suggesting that they were non-ker atinized. It was concluded that the migrating epithelial cells, that c overed the cavity during phenytoin-dependent gingival overgrowth, were of the non-keratinized type.