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
What color does Leishmans stain turn cytoplasmic components?
Pink
What color do white blood cells appear when being stained with Leishmans?
Blue
What blood cell has a bi-lobed nucleus, with bright pink cytoplasmic granules when stained?
Eosinophil
What blood cell has blue stained cytoplasmic granules and a lobed nuclei?
Basophil
Which blood cells has a multi lobed nucleus with pink cytoplasmic granules?
Neutrophil
Which blood cell has an indented nucleus and pale granules in its cytoplasm?
Monocytes
What are elevated eosinophil levels indicative of?
Allergic reactions eg asthma or parasitic infections
In what two circumstances might an increased number of basophils be found?
Chronic myelonous leukaemia
hypersensitivity
What is meant by the term left shift?
An increase in the proportion of band cel,s or the presence of neutrophil precursors in the blood
The presence of what in neutrophils can be an indicator of bacterial infection?
Clear vacuoles
What is seen in a blood film of a patient with CML?
A spectrum of granulocytes cells from myeloblasts to mature neutrophils
What is the definition of megaloblastic anaemia?
anaemia in which maturation of the nucleus is retarded in relation to that of the cytoplasm.
What are the most characteristic features of megaloblastic anaemia that are seen on a blood film?
Hypersegmented neutrophils and macrophages
Oval macrophages
What is the function of the microscope stage?
To hold a microscope slide
How is the degree of illumination of a microscope slide best adjusted?
By changing the lamp voltage
What does a lymphocyte look like on a blood film?
Large round nucleus and relative lack of cytoplasm
What is the key function of a neutrophil?
First line of defense in innate immunity and phagocytose microbes
What are the key functions of monocytes?
Production of cytokines and phagocytosis of microbes and apoptose cells
What are the key functions of lymphocytes?
Production of cytokines - T cells
Production of antibodies - B cells
How are basophils activated?
Cross linking of IgE on their surface to release cytokines
What are the main functions of eosinophils?
Defense against parasitic infections through the release of specific cytokines and also involved in inflammation as seen in asthma and allergy
What are the non-nucleated blood cells?
RBCs and platelets
What are RBCs role, their shape/ colour when stained and their size?
Most abundant blood cell, involved in O2 transport
Biconcave shape, dusky pink
7 micrometers diameter
What are platelets role, their shape/ colour when stained and their size?
These are important in blood clotting, and will probably be found in small clumps on a smear
Bluish
2-4 micrometers diameter
What are lymphocytes role, their shape/ colour when stained and their size?
Small cells with near spherical nucleus and little cytoplasm
Involved in the immune response
around 8 micrometres diameter
What are Eosinophils role, their shape/ colour when stained and their size?
Bi-lobed nucleus. Implicated in fighting parasitic infections and allergy.
Cytoplasmic granules are bright pink.
around 12 micrometers diameter.
What are neutrophils role, their shape/ colour when stained and their size?
multi-lobed nucleus (polymorphonuclear) cytoplasmic granules.
Phagocytic cells which kill bacteria.
10-12 micrometers diameter
What are monocytes role, their shape/ colour when stained and their size?
indented nucleus and pale granules in the cytoplasm. Phagocytic cells with a role in the immune response and inflammation.
17-20 micrometers diameter
What are bosophils role, their shape/ colour when stained and their size?
cytoplasmic granules staining strongly blue
lobed nucleus. involved in inflammation and allergic responses
10-15 micrometers diameter
What are elevated numbers of eosinophils indicative of?
asthma and parasitic infection
