Histopathogenesis of spontaneous periodontal disease in conventional rats: II. Ultrastructural features of the inflamed subepithelial connective tissue

Spontaneously developing gingiitis lesions in the interdental tissue of rats fed a regular pelleted chow and apowdered high sucrose diet were examined in the electron microscope. The subepithelial inlamed connective tissues demonstrated a loss of collagen fibers concomittant with the infiltration of neutrophils, macrophages and lymphocytes. Fibroblasts adjacent to the inflamed gingival epithelium demonstrated cytopathic changes such as dilation of the granular endoplasmic reticulum and diminution of the Golgi complex. Endothelial cells and pericytes were characterized by prominent Gogi apparatuses, numberous mitochondria and well developed granular endoplasmic reticulum. Cytoplasmic processes of both cell types penetrated the vascular basa lamina. Apical migration of the juntional epthelium was preceeded by denudation of the cemental surface by breakdown of the connective tissue attachment. These changes reflect subepithelial tissue breakdwon and a vascular and epithelial micgratory response, probably involving increased synthetic activities.