Histopathology | Medical lab tech
Histopathology is a branch of medical science that deals with the study of tissue and all processing done in the histopathology lab to prepare the tissue for reported by pathologists. The histopathology techniques are done by medical a medical lab technician or technologist and the doctor have to evaluate the result by evaluating the slide under the microscope, the technician has to follow these steps to prepare a thin smear of tissue
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| Histopathology | Medical lab tech |
Histopathology of three Greek words, Histos " tissue" pathos refer to the " suffering and logia " study". microscopic examination of tissue Order to study the manifestation of disease
Especially in clinical Medicine histopathology examination refer to the disease. a biopsy Surgical has been processed and histological sections have been placed on glass slides.
Histopathology | Medical lab tech
Histopathology procedure steps include
- Specimen
- Receiving sample
- Fixation
- Grossing
- Decalcification
- Embedding
- Trimming
- Microtome
- Deparaffinization
- Staining
- Mounting
- Microscopy
- Reporting
- Record the file
Here are some brief introductions of all the steps given above
Tissue sample- tissue part of organs used for histopathology procedure
- Biopsy – a tissue of the living organ
- Autopsy – a tissue of the dead organ
Receiving sample – Sample received in the laboratory.
- Identification
- Serial no
- Fixation used
Fixation- used to fix tissue and its work as a preservative of tissue.
- Purpose
- Types
- Advantage
- Disadvantage
Grossing –this includes the measurement of the tissue and size
- Measurement of tissue size
- Fixation used
- Region of tissue
Decalcification- removing of calcium
- Purpose
- Preparation
- Types
- Advantage
- Disadvantage
Tissue processing – these include these steps
- Fixation
- Preparation
- Dehydration
- Clearing (dealcoholism)
- Impregnation / infiltration
Embedding – Embed the tissue
- Equipment
- procedure
Microtome- cut the section of the tissue
- Microtome types
- Procedure
- Honing
Trimming – to make a thin smear of tissue by using a microtome
Deparaffinization – remove the paraffin from tissue smear
- Purpose
- Types
- Advantage
- Disadvantage
Staining- dye the tissue smear
- Staining types
- Preparation
- Procedure
Mounting – for preserve the tissue slide for a long time so that tissues could be studied further if needed
- Purpose
- Types
- Advantage
- Disadvantage
Microscopy- reporting and record the file
Collection of tissue
His to the pathological examination of starts. with surgery, biopsy, or autopsy. the tissue is from the body & then placed in a fixative which stabilizes the tissue to prevent decay
Grossing
- it is the examination of a tissue sample with eyes & selection of tissue piece for the first of all we have to wear mask & apron,
- Handle trace the tissue after thoroughly washing everyday trace of the fixing fluid dehydrating fluid must be removed before the process
- Make a rough trimming of the tissue sample to make lesional are clearly visible
an instrument used in grossing
Plywood: it should be washed with running water thoroughly after grossing of each specimen.
Grain knife: it is an area used to make a cut off the lesioned area of tissue
Scalpel blades to make small on this cut...
Other's scissors, forceps, wet & dry cotton
Format of the grassing
- Name of the specimen,
- No. of the tissue piece
- size in com os mm,
- appearance,
- color
- consistency.
Procedure :
Make A cut on the lesional area 3.5 mm thickness should not be more than 5 mm. because if the thickness is more processing will be an effect. by proper penetration of the chemical reagent used in processing hold this tissue pièce with the help of forceps & place it on the tissue holder or cassette,
A number tag is placed along with this tissue piece and then the lid of cassete is snapped on Casset now placed in a tissue basket and this is tissue basket is forwarded in the next step.
Fixation
Introduction = this process in which a morphology & molecular composition
Quatilice of good fixations
- Good tissue penetration...
- stabilizes the tissue & preserving the character and distribution of cellular components.
- Prevent structure deformation & mentain shape & volume.
- Preserve cellular constituents
- Prevent fixation art facts.
Types of fixative
1 Formaldehydes
- 20% formalin
- 40% formaldehyde → 100ml.
- Distelled water (D/W) 900 mil
- Buffered neutral formalin :
- Sodium dehydro phosphate - 4 ml.
- Disodium hydrogen phosphate →6.5 ml
- formaldehyde de 100 ml
- D/W → 900 ml
Advantages
- The rapid rate of penetration.
- Reacts with portions", "Unsaturated fully acids & DNA.
- Commercially available.
Disadvantages
- Many reactions are reversible for the most part of fixative is removed with washing.
- A specimen cannot be for any length of time without further stored processing.
2 Jenker's fluid =
- Mercuric chloride 50gm
- Potassium dichromate 25 gm
- Sodium sulfate 25 gm
- D/W - 1000 ml
Add 5 ml glacial citric acid 95 ml of Zenker's fluid before use.
Advantages
it provides excellent fixative of "Nuclear chromatin", "connective tissue fibers, and some. cytoplasmic features.
Disadvantages:
Does not preserve delicate cytoplasm. Organelles such mitochondria.
3.Bouin solution:
- picric acid 750 ml
- 40% formaldehyde :250ml
- glacial acetic acid 10ml
Advantages:
- This fixative is used in histopathology.
- it is especially good for the "gastrointestinal tract" because. this fixation allows nuclear staining than 10% natural buffered formalin.
Disadvantage:
- the acetic acid in the fixative lysis Red Blood cells. and dissolve small iron & calcium.
4. Corney's fluid –
- Absolute alchohole 60ml
- chloroform 30 ml
- Glacial acetic acid = 10 ml
Advantage: this rapid penetrate & gives better nuclear fixation. preserve glycogen.
Disadvantage & May causes shrinkage of cells
Dehydration
Dehydration: Removal of the water from a tissue called dehydration, is done to produce space for the paraffin therefore vax we because have to vax is insoluble in water. Paraffin vax because vax is insoluble in water therefore we have to remove water
Dehydration agent
- is Ascending rate of alcohol (50%, 70%, 80% 90%, 100%.]
- Acetone: it gauze is faster than alcohol and therefore
- Dioxin: it acts as both a dehydration agent as well a clearing agent so when we use dioxin agent as well as clearing agent so when we use dioxin dehydration clearing is when using completely at the same time.
Clearing
Clearing: In clearing pre. alcohol or dehydrating agent removed from the tissue with a chemical reagent which is insoluble in paraffin wax
Clearing agent
- Chloroform = it is slow in action & produces liver disease in water
- Xylene: moat widely use clearing agent it is colorless does not dissolve fat & does not dissolve fat and does not have any harmful effect on the tissue. Rapid action immersion time is not prolonged
- Jolene: it is faster than xylene and it is used for brain tissue
- Dioxin: less damage to the tissue
Impregnation
Impregnation: Paraffin wax is ready to integrate because clearing agent xylene and other clearing agent are unsoluble with paraffin, with paraffin wax entering the natural cavity, Solidyfying, there so firmness is produced in the tissue melting point of paraffin vax is 56°c, therefore, the temperature of their statically control vax both should be above then melting point of should be above then around (60°C)
Embedding
Embedding casting or blocking in the process infiltrated Or impregnated Tissue is placed in warm liquid paraffin the in this process, liquid paraffin, which forms a firm block, after cooking
Embedding enables the tissue to be cut on a microtome. If tissue is oriented in L mold containing perfin vax cut surface to tissue rests flat on to the base of the mold
Tissue embedding systems: these systems are comprised of the following components
- Heated chambers for storage of molds forceps and cassette Both
- paraffin vax (3-5 liiter) reservoir.
- Vax dispenser
- Cold plate adjusted to -5° to +5⁰° temperature. 50 to 60 blocks can be placed on it for cooling
- Drain tray for excess. work vax
Other components:
- tissue take molds they two are used as base mold they are made up of stainless steel two components are used in embedding
Plastic embedding rings: this is the modification of plastic embedding ring embedding cassettes hold tissue for processing ring embedding castes hold tissue for processing
Embedding cassettes: this is the modification of the plastic embedding ring. Embedding cassettes hold processing
Advantages of the tissue embedding system
- Simple to operate and reduce labor
- Improve speed for embedding
- Give to the operation of the tissue
- Provide excellent support while section
- Eliminate steps of attaching the holder to the block
