Histological, cytological and functional organization determine the identity of odontoblasts. These cells are most often aligned in a single layer at the periphery of the pulp. Fully differentiated odontoblasts are tall, columnar, postmitotic cells with a polarized distribution of their cytoplasmic organelles. These cells may be divided into the cell body and the odontoblastic cell process, which probably extends to the dentine-enamel junction. Functional odontoblasts synthesize and secrete collagen type I (and type I trimer), collagen type V and non-collagenous components: proteoglycans, glycosaminoglycans, γ-carboxyglutamatecontaining proteins and phosphoproteins. Two levels of secretion probably exist: most components are exocytosed into the predentine, whilst other components (some phosphoproteins, osteocalcin) appear to be released at the mineralization front. Odontoblasts are connected by junctional complexes; however, these do not completely seal the interodontoblastic space.