Lecture 2- odontogenesis Flashcards
Odontogenesis begins at what week?
6th week of embryonic development
2 basic tissues that arise from ectoderm primary germ layer that play a role in tooth development
epithelial and mesenchymal
odontogenic tissues contain
stem cells that become the specialized cells that form tooth structures
Epithelial stages of odontogenesis
based on?
what are they?
based on histological shape of epithelial tissues in mesenchymal cell environment
- epithelial dental lamina stage
- Bud stage
- cap stage
- Bell stage (with enamel organ that has four layers)
Tooth germ stage
3 parts of tooth germ? derived from what tissue?
odontogenic epithelial and mesenchymal tissues are combined
-cells of each tissue induced to become cells of enamel dentin, pulp, cementum
Enamel organ (epithelial) Dental papilla (mesenchyme) Dental follicle (mesenchyme) -cells from these 3 parts give rise to specialized cells to form tooth structures
Description of first primary dental lamina stage
-At 6th week of development 2 invaginations of epithelial cellsappear anteriorly in mandibular region amongst ectomesenchymal cells. They continue to move on posteriorly and form a facial vestibular lamina band and a lingual primary dental lamina band
facial most epithelial band is the
vestibular lamina
What occurs to form the vestibules
cell death in the center of the facial/vestibular lamina
Lingual most epithelial band is the
primary dental lamina
primary dental lamina becomes
become odontogenic epithelial portion of the tooth germ
cells at deep end of dental lamina will form
epithelial bud surrounded by mesenchymal tissue
primary buds form during?
What teeth do the primary buds form and when?
6 to 8 weeks in utero Central incisors (6 weeks) 2nd molars (8 weeks)
When do permanent buds form?
What teeth do the permanent buds form and when?
4 months in utero to 5 years postnatally
First molar (4 months in utero) Central incisor (5 months in utero) Second molar (10 months post natally) Third molar (5 years post natally)
How many buds arise from the primary dental lamina
16 epithelial buds with 6 for permanent molars and 10 for primary teeth
each succedaneous tooth has
a secondary dental lamina attached to it coming from the lingual side of the primary dental lamina
enamel knot of cap stage is site of
densely full of epithelial cells that signal whether a tooth will become an anterior or posterior tooth
at the bell stage epithelial tissue is aligned in how many layers and what are they
4 tissue cell layers
- Inner epithelial layer
- stratum intermediuum
- stellate reticulum
- outer epithelial layer
secondary dental lamina arises from the
primary dental lamina and not the oral epithelial tissue
Enamel organ forms what
vascular?
Inner epithelial cells differentiate into ameloblasts
- after formation of enamel is complete, ameloblasts as well as other enamel organ layers come together to form a protective layer called the reduced enamel epithelium
- enamel organ is avascularized
Dental Papilla becomes
vascularized?
Odontoblasts, fibroblasts, reserve cells
-ultimately becomes pulp tissue of tooth
It is vascularized
Dental follicle becomes
vascularized?
cementoblast, fibroblast, osteoblast, and reserve cells
periodontal ligament of the tooth
it is vascularized
how is the enamel organ attached to both mesenchymal parts
via the basal lamina
Odontoblasts and ameloblasts found in between
Dental papilla and inner epithelial layer of enamel organ
they are tall collumnar epithelial cells
white space between ameloblasts and odontoblasts from the dentinoenamel junction
Fate of enamel organ cell layers after completion of enamel formation
Come together to form a stratified epithelial layer called the reduced enamel epithelium to protect the tooth enamel until it enters the oral cavity
