The periodontal ligament was examined by light microscopy at 3 different levels (apical, intermediate, coronal) on the 4 root sides of 43 extracted teeth. Epithelial rests were localised and serial LM and EM sections showed a close apposition (up to 0.03 microns) between Ruffini-like and free nerve endings and the basal lamina of the epithelial cell rests. The neural structures were facing the epithelial cells, whereas the Schwann cells were oriented towards the outer connective tissue. The Ruffini-like corpuscles contained numerous mitochondria. Free nerve endings contained neurotubules, neurofilaments and some vesicles. The intimate association between both neuroectodermal structures could indicate a target function of epithelial cell rests during developmental periodontal ligament innervation. Recent immunohistological findings involving nerve growth factor receptors substantiate this hypothesis.