One of the columnar connective tissue cells which deposit dentin and form the outer surface of the dentinal pulp adjacent to the dentin. ("Dorland's Illustrated Medical Dictionary," 24th Edition, W.B. Saunders Company, 1965.)
An odontoblast is a biological cell of neural crest origin that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the creation of dentin, the substance under the tooth enamel. The odontoblasts secrete dentin throughout life, which may be an attempt to compensate for natural wearing down of the enamel. In the case of an infection breaching the tooth to the pulp and killing odontoblasts, Periodontal Ligament Stem Cells may differentiate into odontoblasts which would then secrete reparative dentin.