Introduction to Histology Flashcards Preview

BDS1 - BAMS - Histology > Introduction to Histology > Flashcards

Flashcards in Introduction to Histology Deck (22)
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What is histology

The microscopic study of normal cells and tissue


What is pathology

Study of diseased cells & tissue


What is a carcinoma

Any malignant cancer that arises from epithelial cells


What is metastasis

Spread of disease from one organ to another


What are the advantages of light microscopy

It reveals basic cellular structure & how cells interact with each other
Gives a large field of view
Sufficient to diagnose disease
Wide range of staining methods available which permits identification of tissue features
Many of the stains are polychromatic ie. produce multiple colours in the specimen which helps identify different cellular components


What are the advantages of electron microscopy

Reveals ultrastructure - allows visualization of many features which cannot be seen in light microscopy
it can show a deeper structure of vesicles
Not a lot of stains available for EM however - those available are black and white


What are the 6 steps for the preparation of histology slides

1. specimen collection
2. fixation
3. dehydration
4. embedding
5. sectioning
6. staining


How is specimen collection done

1. Incision/punch biopsy - for skin/oral surfaces
2. Needle biopsy - organs/lumps below the skin
3. Endoscopic biopsy - reach tissue inside body


What happens in fixation

It preserves the structural arrangement between cells and extracellular components
It terminates all biochemical reactions and so prevents tissue decomposition (autolysis)


What happens in dehydration

You need to remove the water to allow wax to penetrate the tissue - water is removed using series of graded alcohols


What happens in embedding

Tissues are too delicate for thin sectioning therefore require support
Resin and wax are most often used as the embedding agent
Alcohol and water are not soluble in wax therefore must be replaced by xylene


What happens in sectioning

Wax is removed from the surface of the block to expose tissue
A microtome is used to cut tissue into a very thin section
Sections are mounted in glass sides
Where the tissue is sectioned makes a big difference to tissue architecture


What is staining

Histological stains are used to provide contrast to tissue sections, making tissue structures more visible and easier to evaluate.


What happens in staining

Most staining solutions are aqueous so to stain sections wax has to be dissolved and replaced with water
Sections passed through xylene and then decreasing strengths of alcohol and finally water
Once stained, section is then dehydrated once again and placed in xylene and mounted on microscopic slide using mounting medium and a coverslip is placed on top
Evaporation of xylene around edges of coverslip bonds it firmly to slide


Name the different staining techniques

H and E
Periodic acid-schiff reaction
Masson trichrome


What is immunohistochemistry

Utilises antibody specificity for antigen therefore any substance (antigen) can be specifically identified provided antibodies for it are available


what does Haematoxylin

stains acidic structures purplish blue


what does eosin stain

stains basic structures red/pink


what does PAS stain

it stains complex carbohydrates magenta


what does masson trichrome stain nuclei



what does masson trichrome stain cytoplasm, muscle, red blood cells and keratin



what does masson trichrome stain collagen