TEST II Flashcards
what name is given to a tissue taken from a patient for histological examination
Biopsy
What process involves a water bath
Tissue flattening
A specimen is examined for identification of specimen/specimen site, name of patient or any unique patient identifier, this statement is true for
Tissue accessioning
in histology what holds the specimen from tissue processing up to sectioning
Tissue cassette
Mention any three devices/apparatus needed during microscopic tissue examination in histology department
- Ruler
- Digital scale
- Tissue cassette
what is the proper tissue fixation ratio for adequate tissue fixation
10:1 or 20:1
which of the following statements is true about tissue fixation
Fixatives can also preserve tissue chemicals
Removal of alcohol from tissue
Clearing
During tissue processing, infiltration is done
after clearing
The first step in hematoxylin and eosin staining procedure is
Removal of parafin wax from the tissue
Which of the following can be used as a blueing agent in hematoxylin and eosin staining procedure
any of the above
mention one advantage of manual tissue processing compared with automated tissue processing
Ability for closer monitoring and intervention during the process, With manual processing, the technician can visually inspect the tissue at each stage. This allows them to identify any potential problems, such as uneven fixation or excessive dehydration, and take corrective measures if necessary.
How do the agitation(stirring) influence the rate of tissue processing
Agitation increases the rate of reaction as molecules of agents and tissue coride
How do the temperatures influence the rate of tissue processing
Higher temperatures generally accelerate the rate of chemical reactions involved in tissue processing. This translates to quicker dehydration, clearing, and paraffin infiltration, leading to shorter processing times.
In tissue processing, the stage after fixation is dehydration.
Why is this stage important
Dehydration removes water from the tissue, making it compatible with the embedding medium, allowing for proper infiltration of the wax throughout the sample
mention any one example of a dehydration agent
acetone alcohol
Mention any three criteria for choosing a clearing agent
1.The clearing agent should be chosen with safety in mind
2. must be cheap
3.The clearing agent should effectively clear the tissue while preserving its morphological integrity
One precaution during tissue flattening using water bath is that the temperature should not reach melting point of paraffin wax or any embedding medium used. Explain the reason for this precaution.
Distortion and Loss of Tissue: If the water bath gets too hot and exceeds the melting point of the paraffin wax, the wax that has already infiltrated the tissue will start to melt. This melted wax can disrupt the delicate cellular structures within the tissue, leading to distortions and artifacts in the final slide.
mention any two examples of embedding media apart from paraffin wax
- Epoxy Resins
- Cryo-embedding Media
- Gelatin
Apart from the tissue block itself, mentioned any three items needed during microtomy
microtome
soft brush
water bath
which of the following are facts concerning tissue clearing agents
all of the above
explain any two ways how dehydrating agents work
- Gradient Replacement: Dehydrating agents, typically alcohols like ethanol, work by gradually replacing the water content within the tissue through a process called gradient replacement.
- Lowering Water Activity: Dehydrating agents also function by lowering the water activity (Aw) of the tissue environment
not one fixative is ideal. agree or diagree
each specimen has its advantages and disadvantages and each one works best on a different specimen than the other
mention an example of dehydrating, coagulative fixative
acetone
for good fixation results tissue thickness should not be more than?
5 mm
Mention any two fixatives that should be avoided including situations when that do not allow their use
- Formaldehyde: avoid when working in poorly ventilated areas. Also avoid using formaldehyde if you need to preserve immunological epitopes in your samples, as it can affect their reactivity.
- Picric Acid. avoided when working around heat or open flames due to its high explosion risk
mention ant two things that are done during microscopic tissue examination before tissue processing
- Gross Examination
- Selection and Trimming
In terms of use what is the difference between an adhesive and embedding medium
Adhesives and embedding mediums both serve to hold things together, but in different ways. Adhesives create a bond between two surfaces, like glue. Embedding mediums, on the other hand, surround and support an object entirely, often used in science for things like tissues or fossils. In short, adhesives connect surfaces while embedding mediums encapsulate objects.
Two reasons why too high concentration of fixative should be avoided
- A very strong fixative concentration can over-harden the sample, making it difficult to stain or perform further analysis
- High fixative concentrations can cause the sample to shrink or distort its natural shape.
How does cold temperature affect rate of tissue fixation
Colder temperatures slow down the chemical reactions involved in fixation. This means it takes longer for the fixative to penetrate the tissue and cross-link the molecules, leading to a slower overall fixation process.
Must harden the tissue making cutting of sections easier but prevent over hardening what is the proceeding statement all about
embedding process with paraffin wax
what is the use of embedding media celloidin
Celloidin excels at supporting tissues that are naturally hard or prone to crumbling during sectioning
