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