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Histology, microscopy, anatomy and disease
Histology, microscopy, anatomy and disease

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1.5 Identify an infection

In this activity you'll identify the tissue and try to identify any abnormality.

Activity 3

Open the virtual microscope [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] in a new window or tab. Find Slide 5 in the ‘Week 4’ category.

Look at Slide 5 and identify the tissue. Try to identify any abnormality in it. You may find it helpful to look back and compare this section with normal tissue. for example Slide 1 in the ‘Week 1’ collection.

When you have noted the appearance of the tissue, think about the pathological changes that can be seen and what is causing them.

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Answer these questions about your findings:

1. What tissue was on Slide 5?

a. 

Lung


b. 

Liver


c. 

Cerebral cortex


d. 

Thyroid


e. 

Lymph node


The correct answer is b.

2. What abnormality did you identify on Slide 5?

a. 

the liver cells (hepatocytes) contain many pale staining vesicles


b. 

there is evidence of haemorrhage (bleeding) into the tissue


c. 

the capsule of the tissue is ruptured


d. 

there are cysts containing a multicellular organism


The correct answer is d.

Answer

This section of liver is from a person infected with a parasitic worm (schistosomiasis). An immature fluke can be seen at [2948, 2145].

3. What pathological processes did you see on Slide 5? Select all that apply.

a. 

acute inflammation with many neutrophils


b. 

chronic inflammation with macrophages


c. 

cell death (necrosis)


d. 

fibrosis – the deposition of fibrous connective tissue


The correct answers are b and d.

Answer

Around the parasites are many leukocytes [2706, 2387] including lymphocytes, macrophages and eosinophils. The parasites have been walled off by fibrous tissue [2759, 2211].

A scientific approach to these slides involves:

  • observation and description of the tissue and any changes
  • interpretation of the findings and possible inferences.

These two stages correspond to the ‘Results’ and ‘Discussion’ sections in scientific papers. The observations and description should be clear, accurate and unequivocal. The interpretation may or may not be correct. A histopathologist will give their best opinion, perhaps with a differential diagnosis (probability) for the underlying cause of any changes in the tissue.

Remember that the finding ‘no unusual features’ is just as important in reaching an accurate diagnosis of disease, as the identification of any histopathological change.