Introduction to Histology Flashcards
Typically how thin is a slice
4 microns
How is bone examined
Demineralised - for thin sections
Ground down (has minerals) - thick slide
What is the most common used dye in combination
Haematoxylin and Eosin(H&E)
H&E
Structured stained
Colours
Nuclei - Blue
Cell cytoplasm - Pink
Extracellular fibres (e.g. collagen, elastic) - pink
Extra-cellular matrix - does not stain
What does PAS stain highlight
Sugars
Good for
- goblet cells in small intestine
- glycosaminoglycans in intestinal brush border
Stains sugars rich magenta
What does Van Gieson stain highight
Elastic
Can be difficult to see on H&E - appears as thick pink bands
See as wavy brownish bands
What does trichrome stain highlight
3 types of cells
- Mucin = blue
Massons’s trichrome (most common)
- Stains variety of different tissues different colours in the same section
What does Alcian blue stain highlight
Mucins
What is size of a cell dependent upon
Function
What is a small cell
Lymphocytes about 10um D with very little cytoplasm
Normally small if they need to move around the body
What is a large cell
Motor neurons 100um wide with axons up to 1 metre in length
What shape are blood cells usually
Spherical
Red blood cells = biconcave discs (appear round)
What cells are fusiform
Smooth muscle cells/fibroblasts
Spindle shaped/elliptical
How are you able to tell where one cell ends and the next starts
Most cells have one nucleus
Can infer where cell membrane is by distance between nuclei and dividing by two
What are dormant/metabolically inactive cells
Generally smaller than metabolically active cells
What are metabolically active cells
Have an abundance of cellular components due to being metabolically active e.g. mitochondria
Commonly have nucleoli - sites of DNA transcription into RNA
What cells last for days
Lining of the gut (small and large intestine) approx. 4-5 days
What cells last for months
Lots of tissues
e.g. blood, skin, connective tissue
How long do red blood cells last for
120 days
What cells last for years
Bones and tendons
What cells last for nearly whole life
(limited regeneration)
Skeletal muscle
What cells last for whole life
No capacity to regenerate
Nerves and brain
Cardiac (heart) muscle
Germ cells
What is the nucleus
Brain of the cell
Surrounded by double nuclear membrane there are numerous small pores to allow passage pf ribosomal RNA and chemical messengers
Contains chromatin
Darked areas - heterochromatin
Lighter colours - euchromatin
What is the nucleolus
1-3um in D
Site of ribosomal RNA formation
What is the mitochondria
Powerhouse of cell
Site of oxidation of phosphorylation
Have own DNA
Double membrane - inner membrane is highly folded (cristae - between = mitochondrial matrix) outside = smooth
What is the function of associated enzymes in the outer membrane of the mitochondria
Lipid synthesis
Fatty acid metabolism
What is the function of associated enzymes in the inner membrane of the mitochondria
Respiratory chain
ATP production
What is the function of associated enzymes in the matrix of the mitochondria
TCA (Kreb’s Cycle)
What is the function of associated enzymes in the intermembranous space of the mitochondria
Nucleotide phosphorylation (ADP to ATP)
What is the rough endoplasmic reticulum
Site of protein synthesis
Highly folded flattened membrane sheets - studded with ribosomes
What is smooth endoplasmic reticulum
Site of lipid synthesis
Processes synthesised proteins
Highly folded flattened membrane sheets - no ribosomes
What is the Golgi apparatus
Parallel stacks of membranes
Processes macromolecules synthesised in the ER
Frequently not visible on light microscopy
Particularly prominent in plasma cells (activated B lymphocytes) - seen as perinuclear ‘hoff’
What are vesicles
Very small spherical membrane-bound organelles
Used for transport, storage and exchanging cell membrane between compartments
Name the types of vesicles
Cell surface derived pinocytotic and phagocytotic vesicles
Golgi-derived transport vesicles
ER-derived transport vesicles
Lysosomes
Peroxisomes
What are lysosomes
Derived from Golgi apparatus
Site where proteins are degraded
H+-ATPase on membrane creates low internal pH (5)
Contain acid hydrolases that degrader proteins
Initial hydrolase vesicles fuse with endosomes with the correct membrane proteins to produce endolysosomes
What are peroxisomes
Small (0.5-1um)
Membrane-bound organelles containing enzymes which oxidise long-chain fatty acids
What is the cytoskeleton
Supports cell shape
Comprised of different types of filaments
What cell does not contain tubulin proteins
Red blood cells (do not divide)
Where is cytokeratins found
Epithelial cells
Where is desmin found
Myocytes (muscle cells)
Where is glial fibrillary acidic protein found
Astrocytic glial cells (supportive cells of nervous system)
Where is neurofilament protein found
Neurons
Where is nuclear lamina found
Nuclei of all cells
Where is vimentin found
Mesodermal cells
What are the intermediate filaments of the cytoskeleton
Cytokeratins
Desmin
Glial fibrillary acidic protein
Neurofilament protein
Nuclear lamina
Vimentin
What are types of tissue
Epithelial
Muscle
Supporting tissues
Nerves
Germ cells
What is the purpose of the epithelia
Protection
Absorption
Secretion
What is a liquid connecting tissue
Blood
Where are lymphocytes found in large numbers
Lymph nodes
Tonsils
Thymus Gland
