Electron microscopic studies on von Korff fibers in the human developing tooth

Deciduous tooth germs were removed from the anterior region of human fetuses between 13‐16 weeks of age and fixed in glutaraldehyde. Some were post fixed in osmium tetroxide whilst others were block stained with silver nitrate and prepared for electron microscopy. Thick Araldite embedded sections were cut at 1 μm and stained in various ways for examination by light microscopy. Thin sections of bulk silver stained material were examined with the electron microscope before and after staining with heavy metals. Fibers lying between the developing odontoblasts were demonstrable under the light microscope and their appearance was consistent with the classical description of von Korff fibers. With the electron microscope bundles of collagen fibers up to 1 μm in diameter were present between newly differentiated odontoblasts. Heavy metal staining of sections from bulk silver impregnated material revealed that silver deposition was associated mainly with collagen fibrils. It is concluded that in the crown of human developing teeth, bundles of collagen fibrils are present between the newly differentiated odontoblasts and that these bundles represent those usually described as von Korff fibers. Similar results were found using material from developing molar teeth of mice.