Tooth Development 1 Flashcards
What’s the very first thing developed in the oral cavity at wk 6?
- primary epithelial band thickens (2 arch shaped bands)
What occurs at wk 7 (after epithelial bands are formed)?
- formation of dental lamina via thickening of primary epithelial band into the underlying ectomesenchymal cells
What’s the induction effect on cells?
- the effect one cell has on another
- signalling molecules bind to receptors -> cascade
What occurs at wk 8 (Bud stage)?
- what does tooth germ look like?
- any histo/morphodifferentiation occurred?
- ‘bulge’
- no morpho/histo
- proliferation of epithelial cells into underlying ecotmesenchyme
- ecotmesenchyme condensing around tooth bud
What occurs at wk 10-12, cap stage?
- What shape?
- any morpho/histodifferentiation?
- ‘cap’ shape
- no morpho
- early histo (IEE, OEE, Stellate reticulum)
- condensation of ectomesenchymal cells = dental papilla + follicle)
What occurs in wk 14, early bell stage?
- what’s the shape?
- any morpho/histodifferentiation?
- morpho-> shape of crown visible
- histo -> IEE cells become columnar
-> peripheral cells of papilla -> odontoblasts - dental follicle encloses papilla that isn’t already enclosed by enamel organ
What occurs at wk 18, late bell stage (after dental follicle formation)?
-what processes occur?
-any morpho/histodifferentiation?
-morpho of crown complete
-histo = pre-ameloblast differentiation from IEE
= odontoblasts -> columnar cells on periphery of dental papilla
-Dentinogenesis
-Amelogenesis
When does amelogenesis occur in relation to Dentinogenesis?
Simultaneously (but dentine matrix is secreted slightly before)
What happens to enamel after amelogenesis?
- Layers of enamel organ are compressed
- REE
- REE fuses with epithelium of oral cavity
- break down of oral dental lamina
Describe the steps in root development following crown formation.
- IEE + OEE loop & form double layered epithelial root sheath at cervical loop (HERS)
- Double layered root sheath (HERS) encloses dental papilla and outlines root shape
- Maintains the same length at all times
- grows apically
- stimulates root formation
- fragments
- repeats
What does the dental follicle form?
Cementum
PDL
Alveolar bone
What occurs after REE forms?
Fuses with oral epithelium
Break down of dental lamina
Rests of Serres