(E1) 3 - Odontogenesis Pt I: Early Tooth Formation Flashcards
Exam 1 - BLANKENSHIP
Mandibular and maxillary arches arise primarily from the ____ with small contribution from ______
PA1
Frontonasal proess
Maxillary premolars and molars arise from ___________
maxillary process of PA 1
Where do all mandibular teeth arise from?
Mandibular process of PA1
Where do maxillary incisors arise from?
Frontonasal region (intermaxillary segment)
The early established oral cavity is lined by stratified squamous epithelium called the _______________
oral ectoderm
Epithelium covers the embryonic connective tissue called ____________
ectomesenchyme
What is ectomesenchyme made up of?
Derived from neural crest cells mixed with mesenchyme
~5-6 weeks of gestation, basal cells of the oral ectoderm proliferate faster creating a thickened band called the
_________________
Primary epithelial band
What does the primary epithelial band indicate?
Position of future dental arches
The primary epithelial band gives rise to two subdivisions. What are they?
Dental Lamina
Vestibular Lamina
What is the dental lamina?
What is the vestibular lamina?
In what direction does the formation of future dental arches occur?
Begins anterior and progresses posterior.
All teeth (and appendages) develop from two germ layers. What are they?
Oral Ectoderm
Ectomesenchyme
What is oral ectoderm?
What is ectomesenchyme?
What tooth structure does the epithelium (oral ectoderm) form?
Enamel
What tooth structures does the ectomesenchyme form?
Dentine, pulp, periodontal ligament, cementum, alveolar bone proper
___________ occurs between dental epithelium and ectomesenchyme → controls dental development
Reciprocal signaling
What steps of reciprocal signaling is ectoderm directed?
Inititaion
What steps of reciprocal signaling is ectomesenchyme directed?
Patterning and Morphogenesis
Reciprocal Signaling: Describe Initiation
Reciprocal Signaling: Describe Patterning
Reciprocal Signaling: Describe Morphogenesis
Chart Image - Germ Layer and Structures
What are the 3 parts of the tooth germ?
Enamel Organ
Dental Papillae
Dental Follicle
What is the tooth germ responsible for?
Forms the mature tooth
What germ layer is the enamel organ from?
Ectoderm
What germ layer are the dental papillae and dental follicles from?
Ectomesenchyme
What does the enamel organ give rise to?
Enamel
What does the dental papilla give rise to?
Dentin and Pulp
What does the dental follicle give rise to?
Cementum
PDL
Alveolar Bone
______________ within primary epithelial band are thought to play a major role in tooth site initiation
Placodes (thickening epithelium)
What are the signal types that affect placodes?
Stimulatory
Inhibitory
Regulatory
Defects in signaling pathways lead to _____________ (3 things)
What does tooth type mean?
What does tooth shape mean?
Morphology
Teeth mature _________ (direction)
anterior to posterior
_____ teeth mature slightly ahead of ______ teeth
Mandibular
Maxillary
What is a succedaneous tooth?
a permanent tooth that replaces a primary tooth
Most permanent develop off the primary tooth dental lamina.
What is the first and last?
What is the exception?
What are the stages of odontogenesis?
_______ determines the site of the tooth
Dental epithelium
- then transfers this potential to ectomesenchyme
What are the characteristic events of the initiation stage?
Where does the dental lamina and vestible form in the mouth?
Lamina = lingually
Vestibule = labially/bucally
The dental lamina indicates initial __________
site of each tooth bud
_______ determines tooth type
Ectomesenchyme!!!!
How do teeth know where to form?
Based on spatially arranged regulatory signaling
What do the oral ectoderm and dental ectoderm give rise to respectively?
Stages of Development: Bud Stage
What is the functional stage and morphological appearance?
What is happening in the transition from the bud to the cap stage?
Stages of Development: Cap Stage
What is the functional stage and morphological appearance?
_________ directs the folding and shape changes of the enamel organ.
Ectomesenchyme
- shape of the tooth is set during this stage (morphogenesis)
In what stage is the shape of the tooth set?
Cap Stage
Characteristic events of Early Cap Stage
Where does the enamel knot appear first?
Early Cap Stage - (more visible in late cap)
Dental epithelium aggregates to form _________
enamel knot
Key roles of the enamel knot
What is the functional stage and morphological appearance of the bell stage?
In what stage does cytodifferentiation occur?
Bell Stage
What are the four layers of epithelium formed from cytodifferentiation of the enamel organ?
What are the characteristic events of the early bell stage?
- the cervical loop is visible
- dental papilla begins differentiating into pre-odontoblasts
- secondary enamel knot appears (only in multi-cusped teeth)
What are the characteristic events of Late Bell Stage?
- cusp formation
Image - Stages of Tooth Development
