Histology- Assessment 1 Flashcards
what do aldehyde fixatives do?
cross link- create covalent bonds between proteins
what do alcohol fixatives do?
precipitate proteins which leads to precipitation and aggregation of proteins
what is NBF?
neutral buffer formalin
an aldehyde that irreversibly cross links proteins at amino groups
what is lost if NBF is used?
ions, mRNA, miRNA, and DNA
what are mercurials good for and why?
immunological specimens because of a slower rate of penetration, get good nuclear preservation in lymphocytes
what is an oxidizing agent? what does it bind to?
secondary fixative used in EM, binds to phospholipids to preserve the membrane
what is an example of an oxidizing agent?
osmium
what is osmium stain used for?
nerves
what is picrate fixative?
precipitating
what affects fixation?
pH osmolarity specimen size fixative volume temperature duration time from removal to fixation
what are some examples of artifact?
specimen shrinkage or swelling
poor penetration
what happens to large macromolecules in fixed samples? what are some examples?
aggregate
nucleoproteins, intracellular cytoskeletal proteins, extracellular proteins, membrane phopholipid-protein complexes
what tissue components are lost during fixation?
ions, glycogen, small proteins, nucleic acids
how is water removed from a specimen?
series of dehydrations
water removed with ethanol
ethanol removed with xylene
then paraffin added
what happens after paraffin is put into a specimen?
thin sections are cut into a ribbon using a microtome
ribbon floated onto a slide
slide baked
after the specimen is on the slide, what next?
paraffin removed by reversing the dehydration process
stained with water soluble dye, dehydrated, stain with ethanol soluble dye
what do acidic dyes bind to?
positive things because they are negative
what is eosin?
an acidic dye that binds to cytoplasmic filaments, intracellular membrane components, and extracellular fibers (positive things)
pink
what do basic dyes bind to?
negative things because they are positive
what is hematoxylin?
a basic dye that binds phosphate groups on nucleic acids, sulfate groups on GAGs, and carboxyl groups of proteins (negative things) *requires an additive pH dependent high pH- binds all groups 5-7- sulfate and phosphate groups <5- sulfate only purple
what does hematoxylin stain?
heterochromatin, nucleoli, cytoplasm with lots of mRNA, ECM cartilage
what is enzyme digestion used for?
as a positive control- destroy what you are staining to make sure you are staining the right thing
what is enzyme histochemistry?
stains the reaction product with a heavy metal
what is immunohistochemistry?
using fluorescent stains to visualize things
direct and indirect methods exist
what is hybridization?
when ssRNA or ssDNA interact with complimentary sequences
detected with radioactive probes of fluorescent dyes on the sequence that will bind to the target sequence
what is FISH?
fluorescent in situ hybridization
used to screen for trisomy 21
what is a benefit of using frozen tissue preparation?
preserves lipid droplets
what does a teased preparation look like? what is it used for?
little strings that are pulled apart
nerves
what does a smear look like? what is it used for?
used for blood, smear sample across to get single layer of cells
what is a spread?
use the whole sample, spread out on a slide
what is a tissue microarray?
up to 1000 samples run at the same time to compare them quickly
what is confocal scanning microscopy?
take many image slices through a sample to reassemble to get a 3D image
what is 2 photon microscopy? what are benefits of using it?
multiple, low energy photons shot at a sample and a photon is emitted
gives clearer points than fluorescence microscopy
prevents tissue damage
what is second harmonic generation microscopy? what is it used for?
photons combine to form higher energy photon when shot at a non linear material
used to determine tumor rigidity
what is TEM?
transmission electron microscopy
sample stained with osmium after being sectioned in plastic
electrons shot at sample and deflection is measured
gives 2D image
what is SEM?
scanning electron microscopy
stain sample after critically drying it
electron beam rasters over the sample and generates a 3D image of the surface topography
what is freeze fracture?
freeze samples and fracture along lipid bilayers to see inside the membrane
what is the e face in freeze fracture technique?
ectoplasmic face- inner membrane
what is the p face in freeze fracture technique?
protoplasmic face- cytoplasm membrane, very bumpy because you can see all the stuff in the cell
what is serial block face SEM?
remove small layers and image each time to reconstruct a 3D image
what is atomic force microscopy used for?
stiffness determination
what are microfilaments used for?
actin- cell movement
what are intermediate filaments used for?
structure maintence
what are microtubules used for?
moving organelles
which end of actin (microfilaments) grows slowly? fast?
pointed end (-) slow growing barbed end (+)- fast growing
what does phallodin stain?
actin
what is non muscle myosin?
same structure as muscle myosin, but used for cell movement
appears as a zigzag pattern inside the cell
how is non muscle myosin regulated?
phosphorylation of regulatory light chain- induces polymerization
phophorylation of myosin heavy chain- inhibits chain interaction
what is the structure of microtubules?
13 alternating chains of alpha and beta subunits in a ring
gamma subunit is used as regulatory
what energy molecule is associated with microtubles?
GTP
in what direction do microtubules grow?
positive end
anchored at negative end
in what structure are microtubules found as a ring of pairs?
cilia
in what structure are microtubules found as a ring of triplets?
centriole
what direction do kinesin proteins move? what do they move on?
retrograde along microtubules
what direction do dynesin proteins move? what do they move on?
anterograde along microtubules
what is the most stable cytoplasmic filament? most dynamic?
stable- intermediate filaments
dynamic- microtubules
what is the structure of intermediate filaments?
alpha helical monomers form coiled coil dimers which associate to form a tetromer that then packs antiparalelly
what is endocytosis?
bringing something into a cell
what is pinocytosis
slightt invagination without clatherin involvement
what is phagocytosis?
antibody binds and antigen and triggers it be brought in
what is receptor mediated endocytosis?
something has to bind a receptor for endocytosis to occur
what stains rough ER?
basic dyes- eosin (blue)
where are simple squamous cells found?
blood vessel lining
air interface in lung
kidney loop of henley
visceral coverings of organs
where are simple cuboidal cells found?
ducts, kidney tubules
where are simple columnar cells found?
digestive tract and female reproductive tract
where are psudeostratified columnar cells found?
respiratory tract, male reproductive tract
where is stratified squamous epithelial tissue found?
keratinized- skin, masticatory areas of oral cavity
nonkeratinized- esophagus, oral cavity lining, vagina
where is stratified cuboidal epithelial tissue found?
ducts
where is stratified columnar epithelial tissue found?
ducts
where is transitional epithelial tissue found?
bladder, ureters, urethra
what are examples of calcium dependent CAMs? what are they for?
cadherins- cell-cell attachment
selectins- cell-cell attachment but WBC can migrate through them
what are examples of calcium independent CAMs? what are they for?
Ig superfamily- WBC migration
integrin- cell-cell or cell-ECM attachment
what is an ADAM protein? what are they for?
a disintegrin and metalloproteinase
prevents integrin attachment to ECM and breaks down connective tissue during embryogenesis, neurogenesis, and angiogenesis?
what is the basal lamina made of?
laminin, fibronectin, type 4 collage
what makes the basal lamina?
epithelial tissue
what is the reticular lamina made of?
type 3 collagen
what makes reticular lamina?
connective tissue
what are the two components of the basement membrane?
basal lamina and reticular lamina
what are microvili?
plasma membrane protection with actin filament core anchored to intracellular actin
what are stereo cilia?
long microvili
what are cilia?
separate organelles that anchor into the cell surface
what is found in basal infoldings?
lots of mitochondria
what are occluding junctions?
tight junctions on apical surface to form seal
what is unique about zonula adhering?
have terminal bar below in an EM
what is the structure of a gap junction?
tubular connexin with 6 subunits, one in each cell
what is hyperplasia?
increased cell quantity
what is hypoplasia?
absence of normal cells
what is hypertrophy?
increase in size
what is atrophy?
decrease in size
what is metaplasia?
change in morphology that is reversible if a stimulus is removed
what is dysplasia?
atypical morphology due to early division of immature cells
what is neoplasia?
persistant abnormality
how are endocrine glands formed?
break away from epithelium, no ducts–>secrete directly into neighboring vessels
how are exocrine glands formed?
stay attached to epithelium, may have ducts, secrete onto surface epithelium
what are goblet cells?
unicellular exocrine glands that secrete mucous
what are gastric glands?
tubular exocrine glands without ducts
what are salivary glands?
acinar exocrine glands with ducts that secrete protein (serous)
what is the pancreas?
exocrine gland
what do serous glands look like at LM level?
darker, lots of rER (pink)
what do mucus glands look like at LM level?
white
what do acinar glands look like?
bunch of grapes
what is merocrine secretion?
vesicles leave via exocytosis
what is apocrine secretion?
some apical cytoplasm is pinched off with secretions
what is holocrine secretion?
the cell disintegrates to release its secretion
what is a poorly differentiated tumor?
not similar to the source of the tumor- poor prognosis
wheat is a well differentiated tumor?
similar to the source of the tumor- good prognosis
what is a papilloma?
benign, from surface epithelium
what is an adenoma?
benign, from glandular tissue
what is an adenocarcinoma?
malignant, from glandular tissue
what does the dorsal root carry
sensory
ventral root carries
motor
sensory ganglia contain
cell bodies of pseudo unipolar neurons
sensory ganglia are part of
dorsal root
the entrance to the sympathetic chain ganglia is through
white rami communicans
the exit from sympathetic chain ganglia is through
gray rami communicans
parasympathetic motor ganglia are
outside cranial nerves and lumbosaccral nerves
what are the types of neuron endings of pseudo unipolar neurons?
modified neurons-
encapsulated endings
unencapsulated endings
proprioceptors
how do modified neurons work?
special cells detect stimulus and gives signal to neuron
examples of unencapsulated neuron endings?
free endings, hair follicle
examples of encapsulated neuron endings
meissner’s corpuscles
pacinian corpusules
ruffini’s corpuscles
where are purkinje cells?
in cerebellum between molecular and granular layers
where are pyramidal cells
cerebrum
where are fibrous astrocytes located?
white matter
where are protoplasmic astrocytes located?
gray matter
where are ependymal cells?
line ventricles of brain and spinal cord
what does the choroid plexus do?
make cSF
what are microglia derived from?
monocytes
what stains myelin well?
osmium- looks like sharpie around the axon
what holds the layers of membrane around the axon together to form myelin?
desmosomes, cadherins, and gap junctions
what happens with a B12 deficiency?
hypomyelination- myelin doesn’t develop in first 2 years so it is missing
what happens in heavy metal poisoning?
demyelination
what is lyme disease?
demyelination secondary to axon degeneration
what is ALD?
adrenoleukodystrophy
peroxisomal disorder involving defects in lipid synthesis and breakdown leading to defects in myelin synthesis
what is MS?
multiple sclerosis
antibodies against myelin formed after some initiating factor
inflammatory response
what is PML?
demyelination caused by reactivation of HPV virus in immunocompromised adults
what is chromocytolysis?
nerve cell swells in response to injury
how is rabies transmitted?
retrograde transport of the virus into the cell body where it proliferates and shed to adjacent neurons
lots of viral particles in cerebellum
what is another term for parasympathetic ganglia?
intramural ganglia
what triggers glial scar formation?
toxin getting through blood vessel in brain and initiating an as astrocytic reaction
what do macrophages look like?
ruffled boarder
high lysosome activity–junk in cytoplasm
what does adipose look like?
light staining
what do mast cells look like?
filled with secretory granules, stained with annular blue that only stains the granules and leaves negative impression of nucleus
what do plasma cells look like?
oval shaped with clock faced nucleus
what is amyloidosis-
intracellular proteins deposited in extracellular area which leads to formation of amyloid plaques in tissues with basement membrane
what is Ehler’s danlos syndrome?
genetic defect in collagen fibril synthesis characterized by join dislocation and skin hyperlasticity
where is type 1 collagen found? what does it look like?
in dense regular CT as large bundles
where is type 2 collagen found? what does it look like?
hyaline cartilage as big fibers
where is type 3 collagen found? what does it look like?
blood forming tissues as reticular fibers that look like thorny threads
what stains reticular fibers?
silver stain
where is type 4 collagen found? what does it look like?
basal lamina, no fibers or polymerization
what does elastin look like?
wiggly thin fibers in annular blue stained sections
what does mesenchyme look like? where is it?
wispy, in immature mesoderm (embryo)
what does mucoid look like? where is it?
a few collagen fibers, more eosinophilic than mesenchyme (pinker), in umbilical cord
how can you tell if you are looking at a section of umbilical cord?
2 veins and an artery will be present
where is loose CT?
under epithelium, more cells present than fibers
what does dense irregular CT look like?
collagen fibers in many directions
what does dense regular CT look like?
packed collagen fibers in the same direction
fibroblasts look like they were pushed out of the way
what does reticular CT look like?
thorny wire, stained with silver
what does reticular CT do?
framework for adipocytes- will look like thorny wire around a bunch of white spaces
what does unilocular adipose look like?
chicken wire, few fibers, white
what does multilocular adipose look like?
lots of darker droplets
what is an abcess?
liquidation of the inside of a fibrotic area
