Which of the following structures is NOT derived from ectomesenchyme (neural crest-derived mesenchyme)?

Ectomesenchyme (also called neural crest-derived mesenchyme or craniofacial ectomesenchyme) gives rise to the dental papilla, dental pulp, dentin, cementum, periodontal ligament, and alveolar bone. The epithelium of the buccal mucosa is derived from oral ectoderm, not ectomesenchyme. Enamel is also an ectodermal derivative (from the inner enamel epithelium of the enamel organ). Distinguishing ectodermal from ectomesenchymal derivatives is key to understanding tooth development and many developmental anomalies.