Observations/ Histology of Different Tissues

Question 1

What is toxicity observed as? What type of observations need to occur to say that toxicity occur?

Answer 1

Toxicity is observed as a pathology and we CANNOT say that toxicity has occurred without observations: visually, physiologically, biochemically, and functionally.

Question 2

What are the types of observations of toxic responses?

Answer 2

There are 3 that we discussed.
1. Testing: a key element of assessing the potential of a chemical to cause harm.
2. Clinical: critical to diagnosing toxic disease.
3. Mechanistic research: provides essential cues as to HOW a chemical might cause disease.

Question 3

What can be observed?

Answer 3

1. Physiological metrics: body weight changes, respiratory parameters, blood pressure, physiological markers in blood.
2. Morphological changes: gross appearance and histological abnormalities in biopsy or postmortem samples.
3. Biochemical markers: proteins and enzymes in blood that reflect tissue damage like ALT (liver and kidney enzyme)

Question 4

What is an example of a biochemical marker?

Answer 4

PCV: red blood cells; high could mean dehydration (too much cells and not enough serum), risk of stroke bc of too many blood cells, or heart issues bc more RBC= more oxygen to body so CHF or lung issues.

TP: total proteins (albumin, fibrinogen, globulins); high amount could indicate dehydration, chronic infection, inflammation, or certain cancers like multiple myeloma AND low amounts could indicate liver or kidney problems, malnutrition, or digestive disorders like celiac disease.

Question 5

What are ways to visualize tissue?
What are the difference between the techniques?

Answer 5

You can do regular staining using Hematoxylin and Eosin Stain, H&E
OR
Immunohistochemistry (IHC)

• Regular Staining: Uses chemical dyes to highlight general structures in tissues, like cell nuclei, cytoplasm, or connective tissue.
• IHC: Uses antibodies to detect specific proteins and their distribution within the tissue.

Question 6

Tell me the difference between Hematoxylin and Eosin staining

Answer 6

Hematoxylin: stains cell nuclei detail, heterochromatin, and nucleoli blue or purple.
Eosin: stains cytoplasm, connective tissue, and collagen pink.

Question 7

Describe what immunohistochemistry is and its process on tissues.

Answer 7

Immunohistochemistry: Uses antibodies to detect specific proteins and their distribution within the tissue.

Process:
1. Introduce a primary antibody that binds to a tissue antigen/ target protein.
2. Introduce a secondary antibody that contains a visual marker/enzyme that will indicate binding.
3. Then, a substrate is added which will react with the enzyme attached to the secondary antibody and produce a brown precipitate/ color wherever the protein of interest is present.

Question 8

1. What staining technique is used for tissues A-C and what types of structures are stained?
2. What types of tissues are slides A-C?

Answer 8

1. They are all hematoxylin (purple) and eosin (pink) stains; hematoxylin stains the nuclei and nucleic acids while eosin stains the cytoplasm and connective tissues.
2. a. Adipose tissue, b. Cardiac muscle, c. Dense irregular connective tissue

Question 9

What type of stain is this?

Answer 9

Immunohistochemistry

Question 10

An 8yo mare presents to the clinic with limping (lameness) in her right rear leg. On examination, part of it appears to be swollen and hot to the touch. Ultrasound with doppler is performed and reveals that a portion of the leg has fluid buildup and decreased blood flow. The veterinarian takes a sample for analysis from the area which shows thick white liquid.

1. What type of cellular injury is occurring and what was the initial cause?
2. Describe the mechanism of cellular injury and stress, include specific changes to cellular organelles.
3. Explain the role of ROS in this case. Include where they would be produced and how they contribute to the pathology seen on presentation.