Oral Developmental Biology: Odontogenesis Flashcards
What do the following terms mean: Histogenesis, Mineralised dental tissues, Unmineralised dental tissues, Dental lamina and Vestibular lamina
Histogenesis- differentiation of undifferentiated cells to make new tissues.
Mineralised dental tissues- enamel, dentine and cementum and Unmineralised dental tissues- dental pulp and periodontium
Dental lamina- contributes to development of teeth
Vestibular lamina- contributes to the vestibule of the mouth, delineating the lips and cheek from the teeth formation of sulcus
What do the following terms mean: Initiation stage, Bud stage, Cap stage, Bell stage, Crown stage and External Enamel Epithelium
Initiation stage- first stage of tooth development
Bud stage- second stage simple, spherical to ovoid, epithelial condensation poorly morphodifferentiated and histodifferentiated.
Cap stage- third stage of tooth development, in which the tooth germ grows into cap shape
Bell stage-Fourth stage, in which differentiation occurs to furthest extent and starts to resemble a bell
Crown stage-Some text books count as a stage-some call it late bell stage-this is with fully developed tooth
External Enamel Epithelium- outer layer of cuboidal cells that limits the enamel organ.
What do the follwing terms mean: Stellate reticulum, Stratum Intermedium, Inner enamel epithelium and Ectomesenchyme?
Stellate reticulum- of epithelial origin but behave like mesenchymal cells-synthesis of Collagen I, II and III.
Stratum Intermedium –two or three layers of cells sitting above IEE. Express Alkaline Phosphatase like SR but not IEE
Inner enamel epithelium- Columnar shaped cells rich in RNA. Connected by desmosomes to each other.
Ectomesenchyme- interesting group of cells whose origin is very controversial. Some think neural crest others mesodermal somites.
What does the Primary epithelial band gives rise to?
- Dental Lamina
- Vestibular lamina
What happens to Vestibular lamina?
Vestibular lamina grows then breaks down and Forms vestibule between teeth and lips/cheeks.
What does Epithelium (ectoderm) gives rise to?
- enamel
- hyaline layer of the root
What does Mesenchyme (ectomesenchyme) gives rise to?
- Dentine
- Pulp
- Cementum
- Periodontium – PDL and bone
Which tissue initiates tooth development?
- Epithelium, ectomesenchyme or nerve?
- Evidence from tissue recombination experiments…..
- Epithelium initially has the odontogenic potential, then the ectomesenchyme
What are the components of a tooth germ?
- Enamel organ
- Dental Papilla
- Dental Follicle
Label this diagram:
Label the diagram:
What is involved in the Early Bell stage?
Morpho- and histo-differentiation
Enamel Organ:
- Inner enamel epithelium
- Stratum Intermedium
- Stellate reticulum
- Outer enamel epithelium
Ectomesenchyme:
- Dental Papilla
- forms odontoblasts (dentine) and pulp
- Dental Follicle
- forms cementum, PDL and bone
What are the Enamel organ components?
Inner enamel epithelium
- Basal lamina conforms to future ADJ
- Columnar cells at cusp tips
- Role: forms ameloblasts → enamel
Stratum Intermedium
- Flattened cells
- Role: Synthesis and transport to and from IEE
Stellate reticulum
- Star shaped
- Fluid filled extracellular space
- Osmotic gradient due to extracellular GAGs
- Role: maintenance of shape and protection
Outer enamel epithelium
- Cuboidal cells
- Role: maintenance of shape and exchange
