IMMS Practical 1 Flashcards
What is the most commonly used dye combination?
Haematoxylin and Eosin
What does haematoxylin stain?
Stains nuclei and other acidic cell components (e.g. RNA) blue.
What does Eosin stain?
Stains cell cytoplasm and many extracellular fibres pink.
Example of a component that doesn’t stain with H&E?
Extracellular jelly
What can white space indicate on a histology slide?
- artefact
- lumen of a structure
- extra-cellular jelly / other unstained component
What is the epithelium?
Border of cells, sometimes around empty space
What does the PAS stain show?
Shows sugars in magenta
What does the Van Gieson stain show?
Elastic fibres and tissues in brown.
What does Alcian Blue stain show?
Stains mucins blue.
What does a trichrome stain show?
Stains different tissues different colours in the same section.
What are the 6 different shapes of cells?
- rounded / globular
- polygonal
- fusiform
- squamous
- cuboidal
- columnar
What is an example of a rounded cell?
Red blood cells
Why are cells polygonal?
Soft cells squashed together
Examples of fusiform cells?
- smooth muscle
- fibroblasts
What do squamous cells look like?
Flattened, like thin plates.
What makes a cell cuboidal?
A cell that is as tall as it is wide
What makes a cell columnar?
A cell that is taller than it is wide
What are some features of metabolically active cells?
Larger, have nucleoli and lots of cytoplasm.
What are some features of dormant cells?
Smaller, less cytoplasm and single nucleolus
What is the function of the nucleolus?
Forms ribosomal RNA
What is the diameter of the nucleolus?
Around 1 - 3 um
What are the 2 types of chromatin?
Euchromatin, heterochromatin
How can you distinguish between the two types of chromatin?
Euchromatin - lighter areas of nucleus
Heterochromatin - darker areas of nucleus
Where is the cell is DNA located?
95% - nucleus
5% - mitochondria
What is the function of the Golgi apparatus?
Processes macromolecules synthesised in the ER
In which cells is the Golgi apparatus particularly prominent?
Plasma cells have a perinuclear ‘hoff’ (a pale area adjacent to the nucleus) which is the Golgi apparatus
What are some features of the nucleus of plasma cells?
- eccentric nucleus, at the edge of the cell
- clock face nucleus - prominent pattern of euchromatin and heterochromatin
- perinuclear hoff - Golgi apparatus
What is the function of the cis face of the Golgi apparatus?
Faces the nucleus, receives transport vesicles from the smooth ER, phosphorylates some proteins
What is the function of the trans Golgi network?
- proteolysis
- sorts macromolecules into vesicles which bud from the surface
What is the function of the medial Golgi?
Central part, forms complex oligosaccharides by adding sugars to lipids and peptides
Diameter of intermediate filaments in the cytoskeleton?
10nm
What is the function of intermediate filaments?
- anchored to transmembrane proteins
- spread tensile forces through tissues
- specific functions generally unknown
Why are intermediate filaments useful clinically?
Immunohistochemistry can be used to identify the intermediate filaments in cells, therefore distinguishing between cell types.
What are cytokeratins and where are they found?
Intermediate filament, epithelial cells
What is desmin and where is it found?
Intermediate filament, myocytes
What is glial fibrillary acidic protein and where is it found?
Intermediate filament, astrocytic glial cells
What are astrocytic glial cells?
Supportive cells of the central nervous system
What is neurofilament protein and where is it found?
Intermediate filament, neurons
What is nuclear laminin and where is it found?
Intermediate filament, nuclei of all cells
What is vimentin and where is it found?
Intermediate filament, mesodermal cells
What is lipofuscin?
A membrane-bound orange-brown pigment.
How is lipofuscin produced?
Produced by the peroxidation of lipids in older cells, common in the heart and liver.
How are where are lipids stored in the body?
Stored in non-membrane-bound vacuoles, found in adipocytes and the liver.
How do stored lipids appear on a histology slide?
Appear as empty space because they dissolve in processing.
What is glycogen? Can it be seen under a light microscope?
A CHO polymer in the cell cytoplasm, normally only seen under an electron microscope.
Why would glycogen accumulate?
As a result of disease, or normally in certain cells.
What are tissues composed of apart from cells?
- interstitial fluid
- extracellular material
What is interstitial fluid made up of?
Water, salts, peptides, proteins
What does extracellular material consist of?
Fibrillar proteins - collagen and elastin, form tendons
Glycosaminoglycan jelly
Solid inorganic salts
What is interstitial growth?
The lengthening of the bone resulting from the growth of cartilage and its replacement with bone tissue.
Where is hyaline cartilage not associated with perichondrium?
Where it lines a synovial joint.
How are cells distributed in hyaline cartilage?
Found in small clusters, move apart as cells secrete extracellular matrix material during interstitial growth.
What are the cells in hyaline cartilage called?
Chondroblasts
What are some features of lymphocytes?
- small, around 10um in diameter
- little cytoplasm
- nucleus occupies 90% of cell
- dormant and undifferentiated until stimulated
- when stimulated, cytoplasm increases in volume
What is the substance in thyroid follicles?
Colloid
What are some features of motor neurons?
- metabolically active
- large cell body to provide metabolic support for the large cell axon & electrochemical gradient creation
- many motor neurons are multipolar, with many dendritic processes
- around 100um diameter of cell body, axons up to 1m in length
What cells have a lifespan of days?
Gut lining
What cells have a lifespan of months?
- blood
- skin
- connective tissues
What cells have a lifespan of years?
- bone
- tendons
What cells live for almost an entire human lifespan?
- skeletal muscle
What cells live for an entire human lifespan?
- nerve and brain cells
- cardiac muscle
- germ cells
What is the function of enzymes associated with the outer mitochondrial membrane?
- lipid synthesis
- fatty acid metabolism
What is the function of enzymes associated with the inner mitochondrial membrane?
- respiratory chain (electron transport chain) for ATP production
What is the function of enzymes associated with the mitochondrial matrix?
TCA (tricarboxylic acid cycle) / Krebs cycle
What is the function of enzymes associated with the intermembranous space?
Nucleotide phosphorylation (the conversion of ADP to ATP)
What is the rough ER
The site of protein synthesis
What is the smooth ER, what it’s function?
Site of membrane lipid synthesis and synthesised protein processing.
What are vesicles?
Small membrane-bound organelles used for transport, storage and exchanging cell membrane between compartments.
What are 5 types of vesicles?
- cell-surface derived pinocytotic and phagocytotic vesicles
- Golgi-derived transport vesicles
- ER-derived transport vesicles
- lysosomes - derived from Golgi
- peroxisomes
What are lysosomes?
Sites for protein degradation
How are cells protected from unwanted protein degradation by lysosomes?
- there is spacial separation between enzymes which lower pH and enzymes which degrade proteins at a low pH
How are lysosomes formed?
Hydrolase vesicles fuse with endosomes, creating an endolysosome.
What is a hydrolase vesicle?
A vesicle which contains enzymes which degrade proteins at a low pH.
What is an endosome?
A vesicle with H+ -ATPase on its membrane, which creates a low internal pH by pumping H+ ions into the vesicle.
What is actin and what is its function?
- forms microfilaments
- 5nm diameter
- globular G-actin polymerises into filamentous F-actin
- actin forms cell cortex to brace the inner surface of the cell-surface membrane
What is tubulin and what is it’s function?
- forms microtubules
- 25nm diameter
- forms scaffold for chromosomes during mitosis and meiosis
- scaffold made of alpha- and beta-tubulin which arrange in groups of 13, forming hollow tubes
What is the function of epithelial tissue?
- protection
- absorption
- secretion
What are germ cells?
Ova / sperm
Examples of supporting tissues (4)
- cartilage
- bone
- tendons
- blood
Why are chondroblasts arranged in clusters in the hyaline cartilage matrix?
The thickening of the matrix prevents migration of daughter cells after mitosis.
Is DNA contained within heterochromatin expressed?
Never expressed as heterochromatin remains permanently condensed.
Is DNA contained within euchromatin expressed?
Yes, as euchromatin decondenses at some point in the life cycle of the cell.
What is chromatin?
Condensed DNA wound around histones.
Does the size/shape of the nucleus change in the normal life cycle of a differentiated cell?
Yes, nucleus enlarges as cell goes from being dormant to metabolically active.
Is there any significance to enlarged nuclei?
May indicate cell malignancy.
What happens to the nucleus if the cell dies?
It is broken down and reabsorbed.
Why might unprogrammed cell death occur?
As a result of necrosis.
What are peroxisomes?
What is their function?
- small vesicles between 0.5 and 1.0 μm in diameter
- contain enzymes which oxidise long-chain fatty acids
