PMI part 2 Flashcards
What is the second step when performing a necropsy?
Skin removal
Measure blubber from these 3 points
WHy analyze prescapular lymph nodes?
- Understand if there is any inflammation ongoing.
- On the level of the pectoral fins
- Only lymph nodes of the body
How to remove bubber?
Gas and fat embolic syndrome
Occurs when gas bubbles or fat droplets enter bloodstream and obstruct blood vessels
Ethical issues of taking skin biopsies from alive animals
- using darts to sample blubber from alive animals
- obtain a cylinder of tissue.
- There are some ethical questions about this method, especially for smaller dolphins like Delphinus or Phocoena it can have a large impact
Information obtained from skin biopsies
Skin samples can be used for…
- Parasitology
- Genetics
Where are heavy metals accumulated?
- Deeper tissues
(In skin: many organic compounds)
Name and sampling site of biggest muscle in cetacean body
- Longissimi dorsi (back muscle)
Third step when performing a necropsy
Internal examination
First step of internal examination
Examining skeletal muscle:
✓ Examine the quality of the fascia and muscle on the body before removing it
✓ Note the color, texture, thickness and abnormalities
✓ Look for hemorrhage, post mortem pooling of blood in vessels (hypostasis or post mortem lividity) and bruising (hematoma)
Capture myopathy
Capture myopathy (CM) is a non-infectious, metabolic muscle disease of wild mammals and birds associated with the stress of capture, restraint and transportation.
3 time based syndromes of capture myopathy
o peracute (characterized by hyperkalemia, cardiac fibrillation and death,
o sub-acute (characterized by tubular nephrosis, renal failure and death;
o chronic (characterized by congestive heart failure, and death.
non-lethal cases: physical impairment such as lameness or loss of the ability to walk or fly (also before death in lethal cases).
Histological findings of Capture Myopathy.
Typical histologic lesions include small areas of necrosis and occasional capillary
microthrombii within skeletal muscle and other organs are commonly reported.
Histopathology
Looking for abnormalities in the tissues under the microscope.
What are the steps for tissue preparation for histology slides?
Target Gram staining (Histology)
gram positive (blue) and negative (red) bacteria
Target Zielh Neelsen staining (histology)
Acid fast bacilli
Target Periodic Acid Schiff (PAS) staining
Glucids, glycogen and basal membrane
Target Masson’s trichromic staining (histology)
Connective tissues (blue), blood (yellow), muscles and epithelium (red)
Target Peerl’s staining (histology)
Iron
What is the goal of histology?
To evaluate tissue’s cells morphology and possible related changes
Immunohistochemistry (IHC) aim and method
- To understand which kind of bacteria or pathogen is present
- (IHC) uses antibodies to detect the location of proteins and other antigens in tissue sections.
Since antibodies are highly specific, the antibody will bind only to the antigen of interest.
The antibody-antigen interaction is then
viewed using either a colored enzyme substrate or a fluorescent dye.
What is important to remember when opening the abdominal cavity?
- Cavity is enclosed, with airways as the only entrance, meaning there’s no direct connection to external air
- The chest cavity maintains a negative pressure, which is essential for lung function.
- Upon opening the chest, you lose this negative pressure, which can impact post-mortem evaluations.
- Presence of air in the chest cavity could indicate a hemothorax (accumulation of blood in the pleural cavity), though confirmation is needed.
- If you hear a sound upon opening, it suggests there was negative pressure, indicating an intact cavity before dissection
Why do diving animals have relatively small lungs?
- for reducing the need for oxygenation and minimizing gas volume to avoid issues at depth
-The rest of the body is also adapted to minimize air volume, protecting it from high pressures during deep dives.
-External pressure increases the deeper the dive
-As pressure increases with depth, having too much air could cause internal damage or “implosion.”
What are the liver and kidneys of diving animals like?
- Liver: very large
- Kidneys: around 200 lobular kidneys that filter blood and conserve water, essential as they don’t drink freshwater.
Even if some kidney lobules are lost, others compensate, providing redundancy.
What is the distinct shape of the ribs in diving animals and why?
-The ribs in diving animals are designed to withstand high external pressure, as “handle-shaped” to increase resilience.
What are the only animals with pulmonary lymph nodes?
- Marine mammals
- Aid in respiratory immunity
How to analyze the lungs when performing a necropsy on marine mammals?
✓ Examine the pleural surface; note color pattern and texture
✓ To examine the internal structures, using scissors, trace the trachea from the bifurcation
along the bronchi and into the bronchioles of each lung
✓ Note fluid, froth and/or parasites are present and describe amount or color
✓ Make serial cuts into the tissue by “bread-slicing” perpendicular to the long axis of the body to examine the parenchyma
✓ Examine the parenchyma and note color pattern and texture
Normal lungs of a diving animal.
- highlight the specialized adaptation of marine mammal respiratory systems
How to open a sea turtle to perform a necropsy?
the plastron (ventral shell) is opened while the turtle is on its back, revealing the pectoral and pelvic muscles for examination
Why are lungs important to analyze during a necropsy?
-Lungs are important to analyze in all animals, as their capillary networks reflect disease or trauma, making them key indicators of overall health.
-The lungs are relatively resistant to autolytic (self-digestive) changes, allowing more time for diagnostic observation.
- They also provide insights into airborne viral transmission.
Steps of working with cardio-vascular system during a necropsy
Name 3 diving adaptations
- Gas exchanges
- Breath-holding diving and respiration
- Heart and circulatory system
How do diving mammals deal with hypoxia?
- They must store oxygen in their lungs, blood, and muscles.
-At depth, gases compress, especially nitrogen (N₂), which has a high affinity (diffuses easily) for fat, making it the most hazardous gas under high pressure.
-Amount of gas moving from lung to blood, from blood to tissue and back controlled by depth, speed of descend and speed ascend and time of dive.
-Lungs are going to collapse progressively, totally collapsed at 70 meters no gas exchange anymore. Just blood to tissues and back. Amount of different gasses regulated by how deep the dive is.
-Frequent diving increases nitrogen levels, leading to a supersaturated state and an increased risk of gas embolism or “the bends” upon surfacing.
-When stranding, it is not unusual to find gas bubbles in blood stream
What is supra/ supersaturation?
The condition of a solution of gases in a tissue having a higher concentration in terms of sum of partial pressures than the ambient pressure.
During ascension, external pressure decreases and tissue partial tension is higher than solubility percentage
What does super-saturation cause?
Bubble formation during decompression phases
What is decrompression sickness?
Presence of large bubbles in the bloodstream
What is the N2 partial pressure in diving seals and in bottlenose dolphins?
- 3 absolute atmospheric (ATA) in diving seals’ blood
- 4 ATA in muscles of diving bottlenose dolphins
What features can help to avoid bubble formation in marine mammals?
- Blood redistribution: Certain areas may receive less blood flow during dives, limiting nitrogen absorption in critical tissues.
- Slow heart rate: dives reduces circulation, which can slow nitrogen uptake.
- Alveolar collapse: Marine mammals’ lungs collapse at specific depths, preventing further gas exchange and minimizing nitrogen absorption
Gas exchange per depth
Bubbles in cetacean tissues
Bubbles in sea turtle tissues
Gas and Fat embolic syndrome: protocol
Opening abdomen and evaluation of:
- mesenteric veins (score 0-6)
- renal veins (score 0-6)
- lombo-sacral veins (score 0-6)
- peri-renal gas (0-6)
- Higher scores typical for bycaught animals
How can seals regulate their dives behaviourally?
- Engaging in many short dives to avoid supersaturation with nitrogen.
What are factors affecting diving behaviour?
- environmental changes and hunting
- E.g. a Risso’s dolphin experienced gas bubbles due to hunting a large squid.
What organ is missing in cetaceans?
Gal bladder
Role of liver and pancreas?
- Crucial roles in nutrient and toxin processing as all blood passes through these organs.
- They are essential in managing pollutants and metabolic waste.
Normal cetacean liver
Cetacean liver showing changes like brownish spots
Cetacean liver showing black spots if stained for mercury salts
Why are hepatocytes widely used as experimental model for studies on liver disease?
- Cell type in parenchymal tissues of the liver
- involved in many liver functions, such as detoxification, carbohydrate metabolism, lipid metabolism, secretion of albumin, clotting factors, and complements
What are Kupffer cells?
Liver resident macrophages
Melano – macrophages in sea turtles:
-Immune functions: phagocytosis, first adaptive response (germinal centers)
-Clearence functions for endogenous/exogenous debris
-Tend to replicate and react
-Melanin in cytoplasm: eliminating diseases
-Try to surround pathogens
-More severe disease: higher nr of melano- macrophages
Spleen peculiarities
-Very small
-20% of dolphins: accessory spleen (more than one spleen) –> when they interact you can have trauma –> particular during mating –> spleen can rapture –> they develop another spleen.
To what organs are the kidneys partially connected?
Reproductive organs
What are all organs wrapped into?
Connective tissue envelopes
What is special about urinary bladder?
- Always empty so cannot sample urine during necropsy
- They don’t have a lot of urine because the kidneys save lots of water
- In very fresh animals –> some chemicals for analysis
Why is kidney useful for toxicology?
Release all metabolic weight, persistent organic pollutants and heavy metals. Can also detect:
-Viral diseases e.g. herpes
-Presence parasites e.g. fin whales have specific parasites for kidneys looooong worms (7-8m). Affect vascular system.
Why gonadal tissue collection?
For life history
Indirect + direct method for diagnosis of infectious diseases
Indirect method Serology = fresh blood fluid
Direct method detection of pathogens
- Puncturing
- Viremia
- Start symptoms develop
- IgM
- IgG
How can brain injuries alter sound transmission and perception?
Echolocation and hearing rely on jaw fat and the melon
Micology
Study of fungi
(Many fungi in marine environment)
Amount of stomachs in marine mammals
- Cetaceans: min. 3, max. 22
- Pinnipeds: 1 stomach
Stomach very thick with strong muscles
Where to look for marine litter ingestion?
Forestomach
Which steps happen when food arrives in the stomach?
food arrives in stomach start chewing food in 2nd chamber through very narrow passage. In 2nd chamber enzymes food digested move through small channels Pyloric stomach ampulla duodenalis
Colours of stomach chambers
- First chamber: white
- 2nd chamber: red
- 3rd chamber: yellow
In circle: lymph nodes
Sea turtles long beak , short eusophagus (has long spikes, so no alive prey will end up in the stomach).
Structure in jaw cetaceans
- To receive sound
- Mandibula fat acoustic fat
- Jaws are filled by fat and nerves (for teeth and pain perception)
Melon
- To transmit sound
- Small lens
- Yellowish
Traumatic lesions to the brain can lead to
- They are not singing, echolocation will change. Different frequency.
- Any injuries to melon or jaw will change perception and transmission of sounds.
- The image in the brain that is formed through echolocation is completely different.
Cochlea
Inner ear
Brain sampling (right and left part)
right part used for virology.
Rest is used for histopathological investigation.
Also investigate if there is any change regarding sound conception.
Analyzing sea turtle brain
Completely useless
