L3: oral histology Flashcards
what are the 3 layers of epithelium in non keratinized oral mucosa
outermost to innermost:
superficial
intermediate layer
basal layer
what are the 4 layers of epithelium in keratinized mucosa
outermost to innermost:
corneal layer (stratum corneum)
granular layer (stratum granulosum)
spinous layer (stratum spinosum)
basal layer (stratum basale)
what is the difference between ortho and para keratinized epithelium
para keratinized got flattened cell nuclei
ortho dont have
what are rete ridges
are epithelial projections into lamina propria
2 kinds of lamina propria
papillary, reticular
what are papilla in the lamina propria
connective tissue projections into epithelium
like interdigitate with rete ridges
defn of hyperkeratosis
thickening of stratum corneum
defn of epithelial hyperplasia aka acanthosis
characterized by increased cell numbers, which usually results in increased thickness of the squamous epithelium
when there is an increase in spinous layer cells, it is called
acanthosis
what is epithelial atrophy
thinning of epithelium associated with decrease in number of epithelial cells
what can counting mitotic figures tell a pathologist
can help to tell benign from malignant or a change towards malignancy
what are mitotic figures
microscopic appearance of a cell undergoing mitosis
instead of a nucleus, chromosomes are visible as tangled, dark staining threads
normal mitosis always happens in which layer in epithelium
basal
in epithelial dysplasia, what happens to nucleus
nuclear size increases leading to increased N:C
what does hyperchromatic nuclei mean and what is it indicative of
dark, strongly stained nucleus
(indicative of proliferative status)
compared to the cells in other layers, basal cells have what kind of nuclei and cytoplasm. as it moved up the layers, what happens?
- basal cells have bigger, darker nuclei and smaller cytoplasm
- as it moves up, nucleus becomes smaller, cytoplasm becomes bigger
- cell flattens out
___ hold keratinocytes together
desmosomes
what does endophytic vs exophytic mean
- endophytic = lesion that appears to grow inwards into underlying tissues (invasive properties, usually more dangerous)
- exophytic: lesion that appears to grow outwards from mucosa
what are the 7 stages of tooth development
1) initiation
2) thickening of dental epithelium
3) bud stage
4) cap stage
5) early bell stage
6) late bell stage
7) root formation stage
in the bud stage, the _____ resembles a small bud
enamel organ
what type of cells form enamel organ?
peripherally located low columnar basal cells
centrally located polygonal cells
supporting ectomesenchymal cells are packed closely beneath and around the epithelial bud
in the cap stage, what types of differentiation give rise to 3 cell types
histo and morpho differentiation
in the cap stage, what is the description of the peripheral cells?
cuboidal, they line the convexity
known as the OEE
in the cap stage, what are the 3 cell types formed?
OEE -> peripheral cells, cuboidal
IEE -> cells lining concavity, columnar
stellate reticulum -> body of the cap shaped ename organ is filled with loose star shaped cells
in the early bell stage, what cells is the IEE made of
short to tall, columnar cells (pre ameloblasts)
in late bell stage, what does IEE differentiate into
IEE in the early bell stage was columnar cells (pre ameloblasts), late bell: differentiate into enamel secreting cells (ameloblasts)
what cells are in the odontoblastic layer of the dental papilla
tall, columnar shaped
what is the layer of cells between the IEE and the stellate reticulum called
what shape are they
stratum intermedium
compressed flat to cuboidal cells
which phase is the reduced enamel epithelium found in
pre eruptive phase
what happens in pre eruptive phase
enamel organ collages and reduces to few layer thick epithelium called reduced enamel epithelium
REE = compressed stratified squamous epithelium derived from compression of ameloblasts, SI and SR, OEE layers
what epithelium is common in a cyst associated with inflammation?
non keratinised stratified squamous epitelium with rete ridge formaiton
dentigerous cyst originates from what
from odontogenic apparatus
we have as many enamel organs as we have ___
teeth
what does ameloblastoma mean
means the px has many many enamel organs, not just the number that corresponds to the number of teeth
what types of cells are in the epithelial islands of a ameloblastoma?
peripheral palisading of tall columnar basal cells and star shaped stellate reticulum-like cells in the centre of the island
osteoblasts are derived from what
osteoprogenitor cells
what are osteocytes
inactive osteoblasts that have become trapped within the bone they have formed
features of osteoclasts
- derived from ___
- break down bone matrix through ________
- single or many nuclei?
- space between osteoclast and bone is known as ____
- derived from monocytes aka macrophages
- break down bone matrix through phagocytosis
- multinucleated cells
- space between osteoclast and bone is known as Howship’s lacuna
what is the composition of bone matrix
osteoid and calcium hydroxyapatite
osteoid = unmineralized matrix composed of type 1 collagen and GAGs
calcium HAP = calcium salt crystal that gives bone its strength and rigidity
what are the 2 types of bone
1) compact/ cortical bone
2) trabecular bone aka cancellous/spongy bone
what is the function of compact bone
what attaches to it
- mainly mechanical function
- is the area of bone to which ligaments and tendons attach
- is thick and dense
what is the function of trabecular bone and where is it located?
mainly metabolic function
located between layers of compact bone
is thin and porous
also located within trabeculae is the bone marrow
where is compact bone usually seen
mostly in flat bones or outermost layer of long bones
compact bone is composed of ___, which are arranged _____ around _____. these areas are called _____
compact bone is composed of lamellae, which are arranged concentrically around Haversian canals. these areas are called osteons
what type of bone is lamina dura
compact
(only that part is compact, the rest of the alveolar bone is cancellous)
cancellous bone is composed of _____ of bone that form an ________ within the bone. the spaces between trabeculae is filled by either _____ or ______.
are haversian system present in the trabeculae?
cancellous bone is composed of trabeculae of bone that form an interconnected meshwork within the bone. the spaces between trabeculae is filled by either red bone marrow or yellow bone marrow.
no, not present
what is woven bone
early bone matrix (osteoid) with many osteocytes and a disorganized matrix structure
woven bone is eventually replaced by _________
lamellar bone
in histo, what colour is woven bone?
lighter pink than the mature bone
osteoclasts lie within concavities known as ____ or ____
howship’s lacunae or resorption bays
