odontogenesis: cellular and molecular Flashcards
hereditary disease affecting bones and teeth
osteogenesis imperfecta (OI)
OI caused by mutations in COL1A1 or ____
type I collagen
OI is ____, in which one mutant allele is enough to cause OI phenotype
autosomal dominant (genotype and phenotype are the same)
need 2 mutant alleles to change the phenotype
autosomal recessive
with autosomal recessive, two ____ are necessary to contribute 2 mutant alleles to offspring
carriers
percent chance of offspring having disease in AD and AR
AD: 50%- usually shows up in every generation
AR: 25%- does not show up every generation
x-linked disease; mutations in AMELX gene on X chromosome
amelogenesis imperfecta (AI)
an affected father with AI passes on mutant X chromosome to _____ only
daughters
The process of a generalized cell becoming specialized for a job (changes in size, shape, products, activities, cell division, etc.)
cell differentiation
the process that initiates differentiation
induction
ability of a cell to receive and respond to a molecular signal
competence
the ultimate generalized cell
stem cell
in cell signaling, ____ chemical signal directs changes in target cells that express ____
secreted; receptors
Proteins that control whether genes will be transcribed into mRNA (to be translated into proteins)
transcription factors (TFs)
DLX3 stands for:
distal-less homeobox 3
DLX 3 regulates what 3 things
- hair follicle differentiation
- enamel genes
- bone
mutations in DLX3 lead to _____
TDO syndrome - tricho-dento-osseous syndrome (hair-teeth-bone)
ball of cells about day 3-4 of development
morula
hollow fluid-filled ball about day 5 of development
blastocyst
inner cell mass of the blastocyst that forms ALL tissues of the embryo- embryonic stem cells
embryoblast
other cells of the blastocyst ; the outer cell layer
trophoblast
___ are established in the blastocyst at about 13 days
axes
with axes established, the embryo is ____ with ___ being dorsal and ____ being ventral
bilaminar (2 layer); ectoderm; endoderm
ectoderm is the floor of the ____; it is dorsal and consists of ____ cells
amniotic cavity; columnar
endoderm is the roof of the _____; is is ventral and consists of ____ cells
second cavity (secondary yolk sac); cuboidal
conversion to a trilaminar embryo, occurs during the 3rd week
gastrulation
____ converge toward the midline to form the primitive streak
ectodermal cells
ectodermal cells migrate thru the primitive streak between ____ and _____ to form a new ____ layer
ectoderm; endoderm; mesoderm
cephalic (more rostral) migrating cells form the ____ to support the embryo
notochord
_____ remains bilayer of endoderm and ectoderm (NO mesoderm)
buccopharyngeal membrane
____ folding happening during week 4; when folding begins, the cardiac plate is ____ to the future buccopharyngeal membrane
rostro-caudal (front-back); rostral
_____ folding also occurs during week 4 and contributes to reorganization to 3D embryo or trilaminar disc
lateral (side-side)
one consequence of rostral-caudal folding
mouth
_____ defines most rostral boundary of the primitive gut
buccopharyngeal membrane
the buccopharyngeal membrane breaks down to allow ____ to communicate with the ____
stomatodeum (primitive oral cavity); foregut
NCCs are induced to undergo _____ transformation
epithelial-mesenchymal
skeletal bones come from ____
mesoderm
during brain development, the ____ expands as:
neural tube expands as forebrain, midbrain, hindbrain
the hindbrain forms ____ _____ or bulges, which define the origins of distinct populations of NCCs
8 rhombomeres
NCCs from midbrain and rhombomeres 1 and 2 contribute to ____
branchial arch 1
NCCs from rhombomeres greater than/equal to 3 express _____, ancient rostral-caudal patterning genes that define body segments
Hox TFs
NCCs that migrate to the face and branchial arch 1 are ____
Hox-free
all TFs include a ____ that allows them to interact with genes
DNA-binding domain
controls the formation of legs during development
HOM-C Homeobox gene
loss of function of HOM-C Homeobox gene causes:
legs–> antennae (loss of body patterning)
gain of function of HOM-C Homeobox gene causes:
antennae –> legs (ectopic expression)
what patterning TFs direct craniofacial development?
Otx2: orthodenticle homeobox 2
Msx: muscle segment homeobox
Dlx: distal-less homeobox
Barx: BarH-like homeobox
NCCs contribute to the ____ in the branchial arches
mesoderm
arches are external bumps which are internally, a mix of ___ and ____
NCCs and mesoderm
the oral cavity is lined with ____ while the rest of the digestive tract is lined with ____
ectoderm; endoderm
branchial arch 1 gives rise to:
- maxilla and mandible
2. meckel’s cartilage portion
meckel’s cartilage gives rise to:
- malleus and incus of middle ear
- sphenomalleolar ligament
- sphenomandibular ligament
branchial groove/cleft 1 gives rise to:
external auditory meatus
pouch 1 gives rise to:
tympanic membrane
tympanic cavity
mastoid antrum
eustachian tube
Dlx1/2 mutant mice show altered ____ and lack of _____
craniofacial morphology; maxillary molars
Dlx1/2 affects ____ BA1 or the _____
proximal; maxillary process
disease caused by failure/impairment of NCC migration to the facial region; causes underdevelopment of craniofacial region and mandible
Treacher-Collins syndrome aka mandibulofacial dysostosis
_____ interactions drive tooth formation
epithelial-mesenchymal
signaling in odontogenesis is described as ____, ____, and _____
reciprocal, reiterative, sequential
which tissue holds the odontogenic potential during initiation stage?
epithelium first, then mesenchyme
morphogenesis begins during the ____ stage of odontogenesis
cap
non-dividing enamel organ cells in the cap stage; expresses numerous signaling molecules; directs proliferation of surrounding epithelial cells
primary enamel knot
2-3 cell layers thick, adjacent to the inner enamel epithelium (IEE)
stratum intermedium (SI)
contains star-shaped cells with lots of space in between them
stellate reticulum (SR)
non-dividing enamel organ cells in bell stage, appearing at sites of cusps (NOT in incisors); express signaling molecules; direct proliferation of surrounding epithelial cells
secondary enamel knot(s)
secondary enamel knot(s) stimulate terminal differentiation of _____ to begin _____ (always begins at cusp tips)
odontoblasts; dentinogenesis
in the late bell stage, the dental papilla forms ____ and the inner enamel epithelium forms _____
odontoblasts; ameloblasts
autosomal dominant mutations in PAX9 transcription factor (expressed in dental mesenchyme early in development)
oligodontia
most oligodontia affected individuals are missing maxillary and mandibular _____
2nd and 3rd molars
autosomal dominant mutations in RUNX2 transcription factor, expressed in dental mesenchyme; causes supernumerary primary teeth
hyperdontia
RUNX2 probably ____ regulates tooth-initating signal like ____
negatively; Wnt
constitutively active Wnt signaling in mouse caused:
- supernumerary teeth
- ectopic enamel knots
- numerous and malformed teeth
embryonic stem cells are _____ and have the ability to differentiate into all 3 germ layers and divide indefinitely
pluripotent
adult (postnatal) stem cells are _____ and have the ability to differentiate within limits; they divide _____
multipotent; asymmetrically (not indefinitely)
dental stem cells have several populations of _____ stem cells
adult/postnatal
Absence of all primary or secondary teeth; tooth agenesis
anodontia
6 or more missing teeth
oligodontia
1-5 missing teeth
hypodontia
more than the normal numbers of teeth (supernumerary teeth)
hyperdontia
dental stem cells can be from what locations?
dental pulp, periodontal ligament (PDL), dental follicle, apical papilla
