Development of the Face, Jaws and Mouth Flashcards
what is a placode?
Area of ectoderm found at the location of the developing special sense organs on the embryo.
what is a nasal placode?
Placodes that develop into olfactory organ for the sensation of smell located in the mature nose.
name this facial swelling
fronto-nasal prominence
name this facial swelling
1st arch
stomatodeum
name this facial swelling
maxillary process
mandibular process
what is pseudofusion of a pharyngeal groove? example?
not true fusion
Groove is eliminated through tissues in the groove proliferating
Between medial nasal prominence
example pseudofusion
what is true fusion between pharyngeal grooves? example?
True separate processes growing towards each other
Between medial nasal prominence and maxillary process
what happens in the 4th week of face development?
Stomodeum bound by the 5 processes (fronto-nasal prominence, mandibular and maxillary processes)
Nasal placodes develop into nasal pits
what happens in the 5th week of face development?
Nasal pit surrounded by lateral and medial nasal prominences formed by differentiation
what happens in the 6th and 7th week of face development?
Medial and lateral nasal prominences fuse together and fuse with maxillary processes
what process is blue?
frontonasal process
what process is yellow?
medial nasal process
what process is pink?
lateral nasal process
what process is light green?
maxillary process
what process is dark green?
mandibular process
what does the frontonasal process form?
forehead and bridge of nose
what does the medial nasal process form?
philtrum of the lip
crest and tip of nose
what does the lateral nasal processes form?
alae of nose
what does the maxillary process form?
cheeks
lateral upper lip
what does the mandibular process form?
lower lip
when does ossification of the mandible occur?
6th-7th week
when does ossification of the maxilla occur?
week 8
when does ossification of the primary palate occur?
week 8
when does ossification of the nasal capsule occur?
week 8
what is intramembranous ossification?
Mesenchymal cells differentiate into osteoblasts which deposit osteoid forming bone.
Osteoblasts also differentiate into osteocytes to maintain bone matrix
what is endochondral ossification?
Bone forming from cartilage
what controls pattern formation?
retonoic acid and growth factors
what growth factors control pattern formation?
BMP, FGF, Shh, Wnt and endothelins
Control cell proliferation, survival and apoptosis
cartilage is a strong, flexible and semi-rigid supporting tissue made by what?
chondroblasts and chondrocytes
functions of cartilage 3
supporting framework of some organs
articulating surface of bone so they don’t rub together and cause damage
template for growth and development where they are gradually replaced by bone
- The surface of most cartilage is ? -> dense irregular connective tissue
perichondrium
what are the two growth mechanisms for cartilage?
interstitial
appositional
what is interstitial growth mechanism of cartilage?
chondrocytes make matrix inside the existing cartilage
what is appositional growth mechanism of cartilage?
chondroblasts from the perichondrium add new surface layers to the pre-existing matrix
what is the main cartilage of the 1st pharyngeal arch?
meckel’s cartilage
meckels cartilage is developed from what type of cells?
crest cells
what growth factor controls the growth of meckel’s cartilage?
CNN2 - connective tissue growth factor
what does a lack in the connective tissue growth factor CCN2 result in?
cleft palates of mice
formation of the mandible
first forms by what kind of ossification? where?
intramembranous ossification -> primary site of ossification is between the incisive and mental nerve
what growth factor is involved in formation of the mandible?
Vascular endothelial growth factor VEGF
development of the mandible
During final development ossification changes to what kind of ossification? where?
endochondral ossification at secondary cartilage sites
formation of the mandible week ?
Mandible first appears as a band of ?? tissue, located where the ?? branches to ? and ??
Formation of bone spreads rapidly ? below the ?? and on the ? side of the ?
? ossification
7
dense fibrocellular
mandibular IAN
mental
incisive nerve
backwards
mental nerve
lateral
IAN
intramembranous
formation of the mandible week ?
Ossification moves away from the ?? to form the ???? following the line of the ??
Cartilage then ? or ? parts of the bones of the ??
10
meckel’s cartilage
ramus of the mandible
mandibular nerve
dissappears
forms
inner ear
in formation of the mandible, what happens just before birth?
secondary mandibular cartilages formed
how do secondary mandibular cartilages differ from primary cartilage?
in secondary cells are larger and have less intracellular matrix
name the 3 secondary mandibular cartilages
condylar cartilage
coronoid cartilage
synphyseal cartilage
what is the most important secondary mandibular cartilage?
condylar cartilage
when does condylar cartilage appear?
weeks 10-12
where is condylar cartilage located?
majority of the mandible
which secondary mandibular cartilage is quickly turned into bone? what type of ossification?
condylar cartilage
endochondral ossification
when does condylar cartilage dissappear?
20yrs of age
when does coronoid cartilage appear?
14-16 weeks
when does coronoid cartilage dissapear?
before birth
where does symphyseal cartilage appear?
in the connective tissue between the two ends of Meckel’s cartilage
when does synphyseal cartilage appear?
week 16
when does symphyseal cartilage dissapear?
1st year after birth
what is osteogenesis?
process of laying down new bone material by osteoblasts
how does osteogenesis work in a developing foetus?
Osteoclasts absorb cartilage as ossification occurs in developing foetus
name this secondary mandibular cartilage
coronoid cartilage
condylar cartilage
symphyseal cartilage
formation of the mandible, understand
