PERIODONTAL NEURAL ENDINGS INTIMATELY RELATE TO EPITHELIAL RESTS OF MALASSEZ IN HUMANS - A LIGHT AND ELECTRON-MICROSCOPE STUDY

The periodontal ligament was examined by light microscopy at 3 differe nt levels (apical, intermediate, coronal) on the 4 root sides of 43 ex tracted teeth. Epithelial rests were localised and serial LM and EM se ctions showed a close apposition (up to 0.03 mum) between Ruffini-like and free nerve endings and the basal lamina of the epithelial cell re sts. The neural structures were facing the epithelial cells, whereas t he Schwann cells were oriented towards the outer connective tissue. Th e Ruffini-like corpuscles contained numerous mitochondria. Free nerve endings contained neurotubules, neurofilaments and some vesicles. The intimate association between both neuroectodermal structures could ind icate a target function of epithelial cell rests during developmental periodontal ligament innervation. Recent immunohistological findings i nvolving nerve growth factor receptors substantiate this hypothesis.