Bell stage of tooth development (late)

During the bell stage, stem cells differentiate into their fully functional forms (cytodifferentiation). The morphology of the tooth is also determined at this time (morphodifferentiation). The dental lamina degenerates while extending a successional lamina, that will produce permanent (successional) teeth.

During the bell stage, stem cells differentiate into their fully functional forms (cytodifferentiation). The morphology of the tooth is also determined at this time (morphodifferentiation). The dental lamina degenerates while extending a successional lamina, that will produce permanent (successional) teeth.

Late in the bell stage the cells of the inner enamel epithelium differentiate into columnar pre-ameloblasts, that later fully differentiate into ameloblasts that deposit enamel.

During the bell stage, the cells of the outer enamel epithelium become cuboidal.

The location where the inner enamel epithelium/pre-ameloblasts and the outer enamel epithelium meet is called the cervical loop. This structure will elongate during root phase of tooth development to form the Hertwig’s epithelium root sheath.

The ectodermal cells within the enamel organ secrete glycosaminoglycans that draw water into the tissue, causing the cells in the stellate reticulum to look star-shaped. The large stellate reticulum allows for the morphodifferentiation of the crown of the tooth. At the cusp to this tooth the stellate reticulum is condensed with the other layers of the enamel organ.

The majority of the ectomesenchymal tissue that differentiates into dental pulp forms the dental papillae.

The enamel organ is surrounded by the dental follicle (dental sac). The follicle is formed by ectomesenchymal stem cells, eventually differentiating into cementoblasts that deposit cementum, fibroblasts that deposit collagen fibers of the periodontal ligament, and osteoblasts that deposit the alveolar bone.

During the bell stage, the dental lamina extends a successional lamina that forms the permanent (successional) teeth.

During the bell stage, the dental lamina extends a successional lamina that forms the permanent (successional) teeth.

The area within the rectangle is shown at higher magnification in the next image.