Lab 3- Characteristics of Tonsillitis Using Histopathology Flashcards
(13 cards)
What is histology?
Histology is an essential tool of biology and medicine. It is the study of the microscopic anatomy (microanatomy) of cells and tissues under a light microscope or electron microscope. Specimens are preserved by embedding and/or freezing and sectioned (cut into a thin cross section with a microtome), stained, and mounted on a microscope slide. The ability to visualise or differentially identify microscopic structures is frequently enhanced through the use of histological stains.
What was the point of lab 3 characterisation of an opportunistic lung infection and characterisation of tonsillitis using histophathology.
Part I: Your first task is to perform a periodic acid-Schiff (PAS) stain in a lung tissue section obtained from an immunocompromised patient, to differentiate normal from infected lung, and to identify the infectious agent.
Part II: Your second task is to analyse pre-stained tonsil slides (haematoxylin and eosin (H&E) stain and immunohistochemistry (IHC)) to further your basic understanding of tonsil structure and function, and to describe changes in response to an upper respiratory tract infection.
List 4csecondary immunodeficiency disorderS
· cancers of the immune system, like leukaemia.
· immune-complex diseases, like viral hepatitis.
· multiple myeloma (cancer of the plasma cells, which produce antibodies)
· AIDS
What is Periodic acid-Schiff (PAS) stain reaction?
Periodic acid-Schiff (PAS) stain is used to stain carbohydrates and carbohydrate rich macromolecules a bright red colour (magenta). This makes it useful to visualise glycogen deposits, neutral mucins and hyphae and yeast-forms. Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans are common fungal species that are PAS reactive.
In the PAS stain histochemical reaction, the periodic acid oxidises the carbon-to-carbon bonds forming aldehydes (Schiff reactive aldehyde groups), which then react to the fuchsin-sulphurous acid to form the magenta colour. The section can be counter stained with haematoxylin and/or a light green.
Why serological investigation is not an accurate diagnostic method in immunocompromised patients?
In immunocompromised patients, serological investigation is considered not an accurate diagnostic method. Immunocompromised people might not make the antibodies and serological tests typically test for antibody presence. DNA detection such as PCR is ideal choice for accuracy.
In case there is a list of choices, below are examples of several serology techniques that can be used depending on the antibodies being studied.
These include: ELISA, agglutination, precipitation, complement-fixation, and fluorescent antibodies and more recently chemiluminescence.
Describe the Waldeyer’s ring
Waldeyer’s ring is a ringed arrangement of lymphoid organs consisting of four tonsillar structures (namely, the pharyngeal, tubal, palatine and lingual tonsils) as well as small collections of lymphatic tissue disbursed throughout the mucosal lining of the pharynx (mucosa-associated lymphoid tissue, MALT).
(The ring surrounds the naso- and oropharynx, with some of its tonsillar tissue located above and some below the soft palate (and to the back of the mouth cavity).
Why is it important to recognise and treat streptococcal tonsillitis early?
If it is treated promptly it keeps the risks down for any complications to arise such as rheumatic fever, and it keeps itv from spreading to other areas. Heart disease is also a risk, it needs to be treated promptly to make sure there isn’t an immune response to the bacteria that looks like itself.
Haematoxylin and eosin stain (H&E) is one of the principal stains in histology. It is the most widely used stain in medical diagnosis. The combination of haematoxylin and eosin produces ______ cell nuclei and ________ connective tissue.
Blue nuclei and violet to red connective tissue
What is Immunohistochemistry? (IHC)
t combines anatomical, immunological and biochemical techniques to more specifically identify discrete tissue components by the interaction of target cell antigens with specific antibodies tagged with a visible label. IHC makes it possible to visualise the distribution and localisation of specific cellular components within cells and in the proper tissue context.
All immunohistochemical protocols depend on primary antibody binding specifically to a target antigen. Antibody bound IHC target antigens are detected through either ________ or _______ means.
Chromogenic or fluorescent means
How does fluorescent detection IHC work?
For fluorescent detection, the primary or secondary antibody is conjugated to a fluorophore that is detected by fluorescent microscopy.
What is the basis of chromogenic detection IHC?
Chromogenic detection is based on the activities of enzymes, most often horseradish peroxidase (HRP) or alkaline phosphatase (AP), which form coloured, insoluble precipitates upon the addition of substrate, such as DAB and NBT/BCIP, respectively. HRP, for example, catalyses oxidation of DAB by H2O2 to form a water- insoluble brown coloured compound: HRP + H2O2 = HRP-H2O2 + electron donor oxidation = colour.
Which cell is proliferating in the tonsil in response to the upper respiratory tract infection?
B cells
