Histology - Cytoskeleton & Ultrastructure Flashcards
What molecules in H&E stained slide stain blue (called what?) and why?
Nucleic acids - DNA/RNA (and therefore nucleus), stain with hemotoxylin due to net negative charge. Termed basophilic b/c they react with basic stain.
What molecules in H&E stained slide stain pink (called what?) and why?
Proteins (and therefore cytoplasm), net positive charge reacts with acidic eosin. Termed eosinophilic.
How is IHC (immunohistochemistry) used?
It is used by targeting cell-specific proteins with brown stained antibodies to detect which cells are expressing a specific type of protein.
What is IHC useful for?
Can be used to detect cancers, and determine treatment based on specific proteins expressed by tumor cells.
What is one way that cells get their specific function that we can see on electron micrography?
Different cells have different number of organelles based on the cell’s specific function.
What are the nuclear pores that line the nuclear envelope for?
Allow mRNA and ribosomes to exit the nucleus.
How does chromatin appear differently based on activity level of the cell, how does it stain?
More active cells have more euchromatin, which is loose and stains lightly, less active cells have more heterochromatin, which is dense and stains darkly.
Where is the rough ER?
next to the nucleus, continuous with the nuclear membrane.
What does mitotic cell division look like in tissue sections under H&E?
Much more deeply stained bars/lines.
Why is identifying the number of cells that are dividing important clinically?
Tells you how fast a tumor is growing.
How do ribosomes stain and why?
Ribosomes stain dark purple/blue (basophilic) because of the RNA they are made up of and contain.
What does the rough ER do?
protein translation (covered in ribosomes)
What happens in the smooth endoplasmic reticulum?
Synthesizing lipids like cholesterol and plasma membrane lipids, as well as steroid hormones, detox of drugs in the liver.
What is the function of the Golgi apparatus?
modifies proteins for secretion, cell membrane, or lysosome (breaks off in vesicles).
How does Golgi appear on H&E
it appears clear because it does not react with H or E
What is the function of mitochondria?
ATP synthesis
What do lysosomes do and how?
intracellular digestion - using hydrolytic enzymes that cut up DNA and phospholipids, as well as acidic internal environment that activates enzymes.
Actin
smallest fiber. allows for movement via polymerization and depolymerization, +/- ends. Also gives shape to cells.
microtubules
largest cytoskeletal filaments. movement. Hollow tubules that grow from an MTOC. +/- end allows expansion and contraction.
How are microtubules controlled?
via GTP hydrolysis and removing or adding pieces.
What is the centrosome/MTOC?
microtubule organizing center. Made up of two centrioles sitting at right angles to each other, and microtubules grow outwards from it.
What are motor proteins and what do they do?
Kinesin - moves cargo away from the MTOC (towards +)on microtubules. Dynein - moves cargo towards the MTOC (towards -)on microtubules. Use ATP to do this.
Intermediate filaments
rope-like filaments, allow the cell to be resistant to tension. provide structural support. non polar.each type of cell makes different ones.
Why is it clinically important that different cells make different types of intermediate filaments?
Can use IHC to stain for types of intermediate filaments in a poorly differentiated cancer cell, and find out what type of cell it is.
