Microscopy and Epithelia Flashcards
What constitutes an organ?
Aggregations of tissues
What is histology?
The study of the structure of tissues by means of special staining techniques combined with light and electron microscopy
What diseases would a doctor not give a diagnosis until the histologists have given one?
Cancers, crohns
How many nanometers in a millimeter?
1 million
How many micrometers in a milimeter?
1000
What is the size of most cells?
10-20 micrometers
What is a biopsy?
The removal of a small piece of tissue from an organ or part of the body for microscopic examination.
What are the 6 types of biopsy, what are they and what tissues are they for?
Smear- collect cells by spontaneous or mechanical exfoliation, smear on slide. For cervix, buccal cavity.
Currettage- remove tissue by scooping/scraping. For endometrial lining of uterus.
Needle- put needle into tissue to gather cells. For brain, breast, kidney, liver, muscle.
Direct incision- cut directly into tissue of interest and remove tissue. For skin, mouth, larynx.
Endoscopic- removal of tissue via instruments through an endoscope. For lung, intestine, colon, bladder.
Transvascular- for heart, liver
Why may biopsy’s need to be fixed and what would they be fixed with?
To preserve the cellular structure, no autolysis or putrefacation.
Commonly used fixatives include formaldehyde and glutaraldehyde.
What can tissue processing lead to and how?
Shrinkage artefacts. During prep of slide tissue is dehydrated and rehydrated
What are two common stains?
Haemotoxylin and eosin
Periodic Adic-Schiff (PAS)
What do each of H&E stain?
Haemotoxylin stains the acidic components of the cell, eg nucleolus (RNA), chromatin (DNA), purple/blue.
Eosin stains the basic components of the cell, eg most cytoplasmic proteins and extracellular fibres, pink
What does PAS stain?
Carbohydrates and glycoproteins magenta
What stains elastic fibres?
Silver stain
What is phase contrast and what are the advantages?
Uses interference effects of two combining light waves. Enhancing the image of unstained cells
What is dark field and what are the advantages?
Exclude unscattered beam (electron/light) from the image. Live and unstained samples.