ABSTRACT
The present study investigated ultrastructurally the recurrent aphthous ulcers [RAU] during its active and healing phases with special emphasis to it's correlation with the possible variable etiological factors. Eighteen Egyptian patients suffering from RAU with no other systemic diseases were included in the present study. Detailed light, scanning and transmission electronic microscopic examination of the excised RAU were performed. The epithelium over RAU area showed de-epithelization and extensive polymorphs and mononuclear infiltrates with perivasculitis. In conclusion, the present study was able to document for the first time the different spatial or temporal ultrastructural changes that occur during an active and healing phases of EAU, moreover, fungal involvement as an etiological factor whether primary or a merely secondary was postulated. Such fungal finding may account for both resistance to medication and recurrence of aphthous ulceration