Ex 1- Odontogenesis Flashcards
_______ is the formation of tooth tissues from stem cells originating in the ________ primary germ layer
Odontogenesis
Ectoderm
Odontogenesis begins in the ______ embryonic week
6th
What are the two basic tissues that arise from the ectoderm primary germ layer that are involved in tooth development?
Epithelium
Mesenchym
_______ is the formation of dentin tissue
Dentinogenesis
______ is the formation of enamel tissue
Amelogenesis
_____ is the formation of cementum tissue
Cementogenesis
Formative levels of the odontogenic epithelial and mesenchymal tissues appear ______ tooth mineralized tissue
before
What is the order in which tooth tissues form?
dentin
enamel
cementum
What are the two histologic stages of odontogenesis?
epithelial stage
tooth germ stage
What are the 4 stages of the epithelial stage?
- epithelial dental lamina
- epithelial bud
- epithelial cap
- epithelial bell (enamel organ)
* epithelial bell stage- epithelium is 4 distinct layers
The _____ ______ stage is when odontogenic epithelial and mesenchymal tissues combine inducing specificity to become formative cells of dentin, enamel, cementum, and pulp tissues
Tooth germ
What are the three parts of the tooth germ?
Enamel organ (bell)
Dental papilla
Dental follicle
* give rise to the specialized cells that form tooth tissues
What tissues make up the 3 parts of the tooth germ?
- epithelium- enamel organ
- mesenchyme- dental papillla + follicle
During the ___ embryonic week, two epithelial invaginations appear (vestibular lamina + primary dental lamina) in the lower anterior region of the lower jaw and later in the week the upper jaw
6th
The epithelial invaginations descend into the underlying mesenchymal tissue (ectomesenchyme) and continue _______ within the mesenchyme as continuous epithelial bands
posteriorly
The ______ arch is 1/2 week behind the _____ arch in terms of development
maxillary
mandibular
The facial band is called ______ lamina
vestibular
The lingual band is called ______ ____ lamina
primary dental
In the most facial epithelial band, _______ lamina, cell death will occur in the center leaving a space known as the ______
vestibular
vetibule
In the lingual most epithelial band is the odontogenic ______ ______ lamina, cells arising from this lamina (primary and secondary) become the odontogenic ________ part of a tooth _____
primary dental
epithelium
germ
Cells at the deep end of the dental lamina, where a tooth is destined to form, will develop into epithelial knobs, each known as an _____ _____ which is surrounded by _______ tissue
epithelial bud
mesenchymal
What is the first mineralized tissue of a tooth?
Dentin
Epithelial bud cells are continuous with cells of the ____ _____ ____
primary dental lamina
Primary buds of central incisors form ___ weeks in utero
6
Primary buds of second molars form ___ weeks in utero
8
How many primary buds are there per arch?
10
Permanent buds of first molars form __ months in utero
4
Permanent buds of central incisors form __ months in utero
5
Permanent buds of second molars form __ moths postnatally
10
Permanent buds of third molars form __ years postnatally
5
There is __ primary dental lamina per arch and __ secondary dental lamina per arch for each succedaneous teeth
1
10
A total of __ epithelial buds arise from the primary dental lamina of each arch: __ primary teeth and __ permanent molars
16
10
6
Each succedanous tooth has its own _______ dental lamina that arises from the _____ side of the primary dental lamina
secondary
lingual
During the cap stage epithelial cells of the cap concentrate to form an ______ _____ which acts as a _______ _____
enamel knot
signaling center
The _____ _____ determines if a tooth will develop to become an anterior or posterior tooth
signaling center
During the epithelial bell stage the epithelial cap undergoes growth and develops into a ___ shaped epithelial structure called an ______ ______
enamel organ
At the bell stage, the epithelium is arranged into ___ distinct cell layers; given names according to position within the bell and cell morphology
4
What are the 4 distinct epithelial cell layers of the enamel organ from inner to outer?
- inner epithelial layer
- stratum intermedium epithelial layer
- Stellate reticulum epithelial layer
- outer epithelial layer
The ____ _____ layer becomes ameloblasts
inner epithelial
Secondary dental lamina is _______ to the primary tooth germ. ___ secondary lamina arise in each arch. ___ for each secondary toth
lingual
10
1
Secondary dental lamina arises from _____ _____ lamina NOT the oral epithelium
primary dental
____ ____ is the epithelial enamel organ and a closely associated __________ tissue that is continuous from around the epithelium to within the epithelium
tooth germ
What are the 3 distinct parts of the tooth germ?
- enamel organ- epithelium
- dental papilla- ectomesenchyme
- dental follicle- ectomesenchyme
The ____ ____ is avascular. Inner epithelial cells differentiate into _______ specialized epithelial cells
enamel organ
ameloblasts
epithelia is avascular
After the formation of enamel is complete, the ameloblasts, along with other layers of the enamel organ come together over the surface of the enamel as a protective structure called ______ _______ ____
reduced enamel epithelium
The _____ ____ is vascular. Its undifferentiated (stem) cells become ____, ____, and _____ ____
dental papilla
odontoblasts
fibroblasts
reserve cells
Dental papilla ultimately becomes ____ tissue of the tooth. _____ are the most numerous cells in the ____ tissue
pulp
fibroblasts
pulp
The dental follicle is avascular. Its stem cells become ______, ____, _____, and _____ ____
cementoblasts
fibroblasts
osteoblasts
reserve cells
The dental follicle ultimately becomes the ______ _____ of the periodontium
periodontal ligament
The enamel organ is attached to both mesenchymal parts of the tooth germ by a _____ _____
basal lamina
The light, acellular layer between odontoblasts and ameloblasts is the site of the future ______ junction (___)
dentinoenamel junction
DEJ
The __ cell layers of enamel organ come together to form a stratified epithelial layer over the enamel surface called ______ _______ epithelium that protects the enamel from surrounding connective tissue until the tooth enters the ______ _____
4
reduced enamel
oral cavity
The ______ _____ at the rim of the epithelial bell (enamel organ) is where inner and outer cell layers merge
cervical loop
Outer and inner layers come together at the cervical loop forming a double epithelial layer called ______ ______ ______ _____
Hertwig’s epithelial root sheath
Hertwig’s epithelial root sheath has what 2 functions?
- Determines:
- root dentin outline
- # root canals of toth
What part of the germ layer and what formative (blast) cell types arose from pulp stem cells?
Dental papilla
- odontoblasts
- fibroblasts
The periodontal ligament was from what part of the germ layer and what 3 formative (blast) cell types arose from its stem cells?
Dental follicle
- fibroblasts
- cementoblasts
- osteoblast
Osteoblasts come from _____ cells while osteoclasts come from _____ _____
stem
bone marrow
What parts of the tooth germ are avascular and vascular?
Enamel organ- avascular
Dental papilla + follicle- vascular
The dental papilla of the primary first molar forms the secondary dental papilla of the permanent first _______
premolar
