Lectures 12 & 13: Histology: Tissues, Epithelium, and Glands Flashcards
How was the meter defined?
10-7 distance from the equator to the north pole
What is the smallest unit of measure the eye can see
1 mm
How big is an RBC?
7-9 micrometers in diameter
How thick is the plasma membrane?
7.5-10 nanometers thick
What is an angstrom?
10-10 meters
By how much does the eye fixture of an LM usually magnify the sample?
x10
What part of the LM can make the magnification vary?
The objective lenses
What is the equation to calculate the resolution of the LM?
Resolution = wavelength x 0.61 / numerical aperture
How does the aperture affect the resolution?
The larger the aperture, the worse the resolution (more blurry)
What is the resolution of LM?
0.2 microns
What is the magnification of LM?
x1,500
What is the definition of resolution?
The ability to distinguish 2 pts that are close together
Explain how the TEM works
- Heat up cathode
- Electrons come up through the cathode and accelerate towards the anode (+ charged)
- E- go through the anode hole
- The sample deflects or absorbs the beam and the beam of e-s goes through sections of a thin grid on which the sample is held
- Beam is reflected on a fluorescent screen releasing photons by different lenses
Whole unit is in a very high vacuum
What replaces the LM objective lenses in the TEM?
The objective lens, the intermediate lens, and the projector lens
What is the resolution of TEM?
1-1.45 nm
What is the magnification of TEM?
x500,000
Describe how SEM works
Similar to TEM: cathode that releases e- when heated (thermyonic emission) towards an anode and passes through electromagnbetic lenses that focus beam on sample. Instead of going through the sample, the beam causes the sample to emit secondary and reflected electrons. It scans the surface but does not go through like in the TEM and as it scans, there is another beam pointing down and you can a 3D image of the surface topography of the sample
What is the resolution of SEM?
2 nm
What is the magnification of SEM?
x100,000
Cell? Microscope?
RBC
LM
Microscope?
TEM
Cell? Microscope?
SEM
Cell? Microscope? Stain?
Kidney
LM
H&E
Cell? Microscope? Blue arrows? Black arrows? Dark black?
Kidney
TEM
Cilia
Mitochondria
Dark black: lysosomes
Cell? Microscope?
Kidney
SEM
What kind of prep needed for LM?
- Fixation (w/ formaldehyde) and dehydration
- Embedding (wax or plastic)
- Sectioning (5-10 microns thick) with microtone and steel knives
- Mounting and staining
What microscopes require dehydration of samples? Why? What is water replaced with?
ALL
LM and TEM because the samples are embedded in plastic or wax which are not miscible with water
SEM because of vacuum environment
Replaced with organic solvent
What is another term for LM?
Brightfield microscopy
What are the 5 common LM stains? Describe each
- Hematoxylin and eosin (H&E): H stains (-) charged and is basophilic and E stains (+) and is eosinophilic
- Periodic Acid - Schiff: stains carbs
- Aldehyde Fuchsin: stains elastic fibers and b-cells of the pancreatic islets
- Orcein: stains elastic fibers
- Silver: stains reticular fibers (collagen)
What does PAS stain?
Carbs
What does H&E stain?
H: nuclei
E: cytoplasm
Cell? Microscope? Small arrows?
Trachea
LM
Small: bleached mucus glands due to dehydration (w/ cilia on the surfaces)
Cell? Microscope? Arrows?
Trachea (with cilia)
TEM
Arrows: liquid preserved in the glands
Difference between cilia and microvilia?
Microvilia are much smaller
Cell? Microscope? Stain? A? F? D?
LM
Intestine cell
PAS
a: glycocalyx
f: mucins
d: lymphocytes
Stain? Cell? Microscope?
LM
Silver
Golgi
What prepartion is needed for TEM?
- Fixation (with osmium tetroxide that preserves lipid) and dehydration
- Embedding in beam capsules
- Polymerization of capsules in oven
- Remove sample from mold
- Trim for ultrathin sectioning with diamong or glass knives
- Sample collected on grids (many different types) in a boat of water
- Staining to impart different electron density with heavy metals (lead and uranium salts) to different parts of the cell
How is the fixation process different in LM and TEM?
LM: wax or plastic, thicker
TEM: only plastic, thinner, more sophisticated
Microscope?
TEM
A? B?
A: microvilli labelled with gold particles
B: aquaporins
What is freeze fractioning?
Another EM technique where we fracture the cell through the middle of the bilayer and expose the proteins embedded in the membrane (E and P faces)
What is the prep needed for SEM?
- Fixation & dehydration (because it goes in a vacuum)
- Coat it to accentuate the release of e-s from sample
THAT’S IT!!
Which microscope requires the least prep?
SEM
What is this?
Cilia on trachea (goblet cells)
Electron beam different in SEM and TEM?
Nope
Same fixation process in LM and TEM?
Nope
At the LM level can you see ribosomes? Microtubule? Microfilament? Basal body?
No
No
No
YES!
What are 8 characteristics of epithelial cells?
- Cover/Line all surfaces in the body except for joint cavities
- Lie on basal lamina of the basal membrane
- Avascular
- Polarity: apical and basolateral portions
- Keratin filaments provide strength and desmosomes makes them act like a continuous sheet
- Many have remarkable renewal capacity (like skin and intestines)
- Derived from 3 germ layers: mesoderm, ectoderm, endoderm
- Diversity in function: secretory, protective, absorptive
Do epithelial cells have veins?
NOPE
How do you distinguish the basement membrane from the basement lamina?
Membrane: you can see with LM
Lamina: EM level
What are surface epithelia classified by?
- # of cells in epithelium: simple/stratified
- Height and shape of surface layer of cells: squamous/cuboidal/columnar
Simple squamous epithelium: shape? what do they line? shape of nuclei?
Flat
Body cavities, blood vessels
Round nuclei
Simple cuboidal epithelium: shape? shape of nuclei?
Cube
Flattened nuclei
Simple columnar epithelium: shape? shape of nuclei?
Tall
Eliptical nuclei
Type of epithelial cell?
Simple squamous
Blood vessel!!
Type of epythelial cell? Where?
Simple cuboidal
Kidney collecting duct
Why does the nuclei seem to be missing on certain cells?
Not part of the cut plane in sample
Type of epithelial cell? Where?
Simple columnar
Small intestine
What are the stratified epithelium cells named based on?
The surface cells
What are the 3 types of stratified epithelium? Describe each
- Stratified squamous/cuboidal/columnar
- Ciliated pseudostratified: not actually stratified but nuclei are at different levels
- Transitional: dome shaped (very unique) which can squeeze and slide over each other
Where are transitional epithelium cells found?
Urinary passages: ureter, bladder (what brings urine from kidneys to bladder)
Type of epithelial cell? Where?
Stratified squamous (nonkeratinized)
Esophagus
Type of epithelial cell? Where?
Stratified squamous keratinized
Thin skin
Type of epithelial cell? Where? What is the pink?
Stratified squamous keratinized
Thick skin
Pink: epidermis
Type of epithelial cell? Where?
Stratified cuboidal
Sweat gland duct
Type of epithelial cell? Where?
Stratified columnar
Salivary gland duct
Type of epithelial cell? Where?
Pseudostratified
Trachea (and all respitatory passages)
Type of epithelial cell? Where? Arrow?
Transitional
Bladder
Binucleation (common for transitional epithelial cells)
What are glandular epithelia specialized for? 2 types? Main one?
Secretion
- Parenchyma: secretory cells of the gland (main type)
- Stroma: connective tissue in glands supporting the parenchyma
What are the 2 main types of glands?
- Endocrine: secretory product passes directly into blood
- Exocrine: have ducts to convey product to surface of body or cavity or hollow organ
How do we classify the different types of exocrine glands?
- Shape: tubular (coiled or branched) or acinar
- Compound (branching ducts)/Simple (only one duct)
How can we categorize all glands regarding their secretion?
- Type of secretion:
(a) Serous: watery secretion: acinar, stained, nuclei are round and located in center
(b) Mucous: viscous secretion: cytoplasm is bleached out during histo so you cannot stain it (appears clear), cuboidal cells w/ flat nuclei - Mode of secretion:
(a) Merocrine (most): product release w/o loss of membrane
(b) Apocrine: whole apical portion of cell is the product
(c) Holocrine: whole cell is the product
What do you call the serous glands when connected to mucous glands?
Serous demilune
What is the mode of secretion of mammory glands?
Apocrine
What is the mode of secretion of sebaceous glands (skin: oily)?
Holocrine
Black arrows? White arrows?
Microvilli brush border
Lymphocytes
What are these? Where? What microscope?
Microvilli
Small intestine
SEM
Each line?
Left to right:
Filaments
Terminal web
Microvilli
Cell coat
Arrows?
Left to right:
Microvilli
Microfilaments
Cell coat (bottom)
Black? Blue?
Cilia
Basal bodies
Arrow? Yellow? Microscope?
Cilia (also very small microvilli above goblet)
Basal bodies
TEM
What is this?
Cilia
What is this? Where? Microscope?
Stereocilia in ductus epididymis
LM
What is this? Where? Microscope?
Stereocilia
Ductus epididymis
SEM
What is this? Where? Microscope?
Stereocilia
Ductus epididymis
TEM
What is this? What do they do?
Microplicae: folds in surface of non keratenized squamous epithelium
Found in oral cavity vagina, anal canal, under the eye
Hold a layer of mucin to protect surfaces from trauma
What microscope needed to see the ER?
EM
What can you stain cells that have a cytoplasm rich in ribosomes?
Basophilic dyes (like hematoxylin) because RNA is extremely basophilic
What is immunohistochemistry? 2 types?
Specific substances are stained in sections by the use of antibodies that are linked to a fluorescent compound or to an enzyme that can give rise to a colored precipitate in presence of a specific substrate
- Direct method: primary antibody is labeled
- Indirect method: second antibody directed toward the first is used to amplify the rxn
