In vertebrates, an odontoblast is a 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 formation of dentin, the substance beneath the tooth enamel on the crown and the cementum on the root.

The odontoblastic cell body keeps its tapered structure with cytoskeletal fibres, mainly intermediate filaments.

Unlike cartilage and bone, as well as cementum, the odontoblast's cell body does not become entrapped in the product; rather, one long, cytoplasmic attached extension remains behind in the formed dentin.

[8] Odontoblasts first appear at sites of tooth development at 17–18 weeks in utero and remain present until death unless killed by bacterial or chemical attack, or indirectly through other means such as heat or trauma (e.g. during dental procedures).

Thus, dentin and pulp tissue have similar embryological backgrounds, because both are originally derived from the dental papilla of the tooth germ.

In the case of an infection breaching the dentin to or very near the pulp, or in the instance of odontoblast death due to other attack (e.g. chemical or physical), undifferentiated mesenchymal cells can differentiate into odontoblast-like cells which then secrete another type, reparative dentin, underneath the site of attack.

Histologically, it is easily distinguishable by its disordered tube structure, the location of the secretion (it protrudes into the pulpal cavity) and its slightly lower degree of mineralization than normal.