Diagnostic Role Of Blood Film Flashcards
What is a blood film?
A method of blood sample preparation which allows red blood cells, white blood cells and platelets to be spread evenly for microscopic inspection
What is microscopy?
A technique used to examine samples (tissue, fluid, cells) that are too small for the human eye to see unaided
Is all blood considered high risk?
yes, so a lab coat and gloves must always be worn
What are the stains used?
Haematoxylin and eosin
What does Haematoxylin bind to?
Acidic components of cells - particularly to DNA and therefore shows up in the nucleus
What other stain works similarly to haematoxylin?
Leishman’s
What is the colour of haemotoxylin?
purple-blue
What does Eosin stain?
Binds proteins components, particularly in the cytoplasm
What colour is eosin?
bright red synthetic dye, but stains pinkish
What does Leishman’s Stain do?
Makes the nucleus visible
Why are eosinophils called eosinophils?
They are cells with granules which were readily stained by the dye eosin
What affects the performance of a light microscope?
The wavelength of light (you can’t alter this system)
The optical quality of lenses and all other components in the light path
The refractive index of the medium through which the light passes (which is why the highest resolution lenses are designed to use oil instead of air between the objective lens and the slide)
The physical properties of the objective lens
What is the numerical aperture?
The numerical aperture of a microscope objective is the measure of its ability to gather light and to resolve fine specimen detail while working at a fixed object (or specimen) distance (not the same as resolution- but the higher the numerical aperture the higher the resolution)
It is written on the lens next to its magnification
(e.g., 10/0.25, means that the lens has a 10x magnification and a numerical aperture of 0.25)
It follows that higher magnification does not necessarily mean higher resolution
What is the field Iris?
The light that comes from the bottom of the microscope
What are the 2 types of light microscopes used?
Leitz microscope
Nikon microscope
Are you comfortable naming parts of a microscope?
What lens is it best to start with during microscope based practicals?
The Lowe power objective lens (4x)
What is the correct order in which your should focus your image?
- Focus the image
- Focus the condenser
- Adjust the field Iris
- Adjust the condenser Iris
How should blood be smeared onto the slide when preparing a blood film?
Place a drop of blood onto the glass slide and smear it away from you using a second piece of glass as a spreader - this ensures the blood drop stays behind the spreader otherwise blood cells might become damaged between the two slides
What color does Leishmans stain turn nuclei?
Purple - blue