7th seminar-tissue processing & embedding.pptx
TRANSCRIPT
![Page 1: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/1.jpg)
Good morning
![Page 2: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/2.jpg)
- By Dr Shruthi B S
Tissue
Processing
![Page 3: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/3.jpg)
References • Theory and Practice of histological
techniques, 6th Ed - Bancroft.• Cellular pathology technique, 4th Edn-
Culling• Theory & practice of Histotechnology,
2nd Edn – Sheehan• AFIP laboratory methods in
Histotechnology• Histopathology Techniques: Tissue
Processing and Staining, Dr. S.I Talukder
• Internet
![Page 4: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/4.jpg)
Presentation outline• Introduction• Specimen handling• Tissue processing• Factors affecting tissue
processing• Stages of tissue processing• Methods of tissue
processing• Conclusion
![Page 5: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/5.jpg)
Introduction • The most commonly used
method of examining tissue microscopically is by sectioning
• Fixation of the tissue stabilizes the structure and stabilised tissues must be adequately supported by infiltrating and embedding in support medium before they can be sectioned for microscopical examination
![Page 6: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/6.jpg)
Specimen handling
• Correct labelling & identification are the first essentials of processing
• Emphasis should be given to1. A foolproof system of labelling2. Ensuring the correct label
remains with the specimen throughout
3. Constant vigilance
![Page 7: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/7.jpg)
Labelling of tissues(a)Handwritten in soft lead pencil or
waterproof ink (b)A numbered card label generated by
computer-printer(c)Automated embossing systems that
permanently etch or emboss tissue cassettes and slides and produce serial numbers
(d)Tissue- Tek system – where tissue identity is written on cassette & retained as permanent record
![Page 8: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/8.jpg)
Tissue Tek System
• The cassettes consisted a small perforated plastic container with metal or plastic lid
• Edges of the cassettes are roughened enabling them to be marked in pencil
• As the cassette forms a part of final wax block, the id number stays with the specimen from the time its put in and thus reduces the margin of error
![Page 9: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/9.jpg)
Tissue processing• Definition It refers to any treatment of
the tissue necessary to impregnate them with a solid medium to facilitate production of sections for microscopy
![Page 10: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/10.jpg)
Principle of tissue processing
• Fick's Law: The rate of solution diffusion through tissues is proportional to the concentration gradient as a multiple of temperature dependant constants for specific substances.
• Tissue processing is concerned with the diffusion process results from the thermodynamic tendency of processing reagents to equalise concentrations inside and outside blocks of tissue and thus stabilize it
![Page 11: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/11.jpg)
Factors affecting the rate of processing
Tissue processin
g
Specimen size
Heat
Agitation
Viscosity
Vaccum
![Page 12: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/12.jpg)
1. Specimen size:• Thicker the specimen, longer will be the
impregnation• Ideally, specimen thickness has to be 3-
4mm• If thicker slices are unavoidable,
processing schedule has to be prolonged 2. Heat:
• Increases the rate of penetration & fluid exchange• Temperature is limited to 45ºC• Disadvantages:
– Hardens tissue, increases brittleness, shrinkage
– Interferes with staining
![Page 13: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/13.jpg)
3. Agitation:• The greater the surface area of the tissue in
contact with processing fluid, more effective the fluid interchange.
• Agitation ensures the effective interchange between fluid within the tissue & fluid outside
• Commercial tissue processors has automatic agitation with either vertical or rotatory movements of specimen container or by drawing & refilling the containers
![Page 14: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/14.jpg)
4. Viscosity: • Higher the viscosity of processing fluid,
slower the rate of penetration.• Clearing agent like cedarwood oil &
molten wax are of high viscosity and require longer immersion times to achive impregnation.
• Heating reduces viscosity but this is avoided when using cederwood oil as this causes tissue hardening
![Page 15: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/15.jpg)
5. Vaccum:• Vacuum reduces the time necessary
for impregnation by one-half particularly dense and fatty tissues
• Helps in removal of trapped air from tissues
• Assists in the removal of clearing agents because of increased volatility
• Some Automatic processing machines incorporated vacuum at all stages of processing cycle
![Page 16: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/16.jpg)
Stages of processing
Dehydration
Clearing
Impregnation
Embedding
Removal of water and fixative from the tissue
Removal of dehydrating solutions Permeating the tissue with a supporting mediumOrienting the tissue sample in a supporting medium
![Page 17: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/17.jpg)
Dehydration • First stage of processing concerned with
the removal of unbound water and aqueous fixatives from the tissue components
• Specimens are processed in a graded series of reagents of increasing concentration to prevent its distortion
• Excessive dehydration- hard, brittle & shrunken tissue
• Incomplete dehydration- inhibit the penetration of clearing agents
![Page 18: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/18.jpg)
Duration of dehydration
• Duration of dehydration should be kept to the minimum consistent with the tissues being processed.
• Tissues may be held and stored indefinitely in 70% ethanol without harm.
Specimen Time For whole organ 24-48 hrs in each
For delicate tissue & cytological research
2-4 hrs in each according to size
For post mortem tissue of not > 7mm
70,90,100% (3 changes) for 1-2 hrs in each
![Page 19: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/19.jpg)
Dehydrating fluids• Dehydrating fluids should be
water miscible• Choice of a dehydrant is
determined by the nature of the task, the embedding medium, processing method, and economic factors
• Dehydrants differ in their capacity to cause tissue shrinkage
![Page 20: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/20.jpg)
Concentration of dehydrants
• The dehydrant concentration at which processing is initiated depends largely upon the fixative employed
70%Specimen Concentration of dehydrant
Embryonic tissue in aqueous fixative
10%-20%-50%-95%-100%
Tissue in carnoy’s fluid 100%
Most specimens in aqueous fixative
70%-80%-100%
![Page 21: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/21.jpg)
Use of copper sulphate in final alcohol:
• A layer (1.2 – 5mm thick) of Anhydrous copper sulphate added to the final absolute ethanol on a tissue processor scavenges any water present
• The salt is self-indicating: white when anhydrous, blue when hydrated
• This action not only speeds the dehydration process of tissue but also prolongs the life of alcohol
![Page 22: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/22.jpg)
Ethanol • Clear, Hydrophilic, miscible with
water and organic solvents• Rapid, efficient, widely applicable
& most commonly used dehydrant in histology
• Ensures total dehydration, making it as choice for the processing of electron microscopic specimens
• The volume of alcohol should be 50-100 times that of tissue
![Page 23: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/23.jpg)
Advantages • Nontoxic• Miscible in all
proportions of water• Little shrinkage • Fast acting• Reliable
Disadvantages • Expensive• Longer period may
cause shrinkage• May have prohibitive
taxes• Extracts methylene
blue from sections
![Page 24: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/24.jpg)
Methanol
• It is a good ethanol substitute but rarely used for routine processing because of its volatility, flammability and toxicity
• It is miscible with water, ethanol & organic solvents
• In microwave processing it tends to harden tissues more than ethanol
![Page 25: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/25.jpg)
Isopropyl alcohol
• Miscible with water, ethanol and most organic solvents
• Often used in microwave processing schedules
• Does not cause overhardening or shrinkage of the tissue
![Page 26: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/26.jpg)
Acetone • Clear, colourless, flammable
fluid miscible with water, ethanol and most solvents.• Has characteristic pungent
odour• Rapid in action, with poor
penetration & Causes brittleness of tissue if use is prolonged.• Removes lipids from the tissue
during processing
![Page 27: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/27.jpg)
Additives
• Phenol- (4%) softening agent for hard tissues like tendon, nail, keratin masses
• Hard tissue can be mixed even in alcohol-glycerol mixture
![Page 28: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/28.jpg)
Clearing • Clearing is the transition step
between dehydration and infiltration with the embedding medium
• Dehydrants are immiscible with paraffin wax, and a solvent miscible with both the dehydrant and the embedding medium is used to facilitate the transition between dehydration and infiltration
![Page 29: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/29.jpg)
Why is it named so??
• The term clearing arises because some solvents have high refractive indices approaching that of dehydrated fixed tissue protein and, on immersion, anhydrous tissues are rendered transparent or clear
![Page 30: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/30.jpg)
Criteria
• The type of tissues to be processed, and the type of processing to be undertaken
• Rapidity of removing dehydrating agent
• Ease of removal by infiltrating agent
• Minimum tissue damage• Toxicity & inflammability• Cost and convenience
![Page 31: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/31.jpg)
Clearing agentsXylene & Toulene:• Flammable, colourless, miscible with
most of the organic solvents & paraffin
• Rapid in action, 30-60 min for small pieces of tissue and about 2-4 hours for 5mm thick specimens
• Toulene has same properties as xylene but less damaging to tissue and more volatile
![Page 32: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/32.jpg)
Advantages • Clears quickly• End point is easily
determined• Used for clearing in
staining sequence• Recyclable
Disadvantages • Flammable• Hardens the tissue• Toxic to skin &
various systems of body
• Not miscible with water
![Page 33: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/33.jpg)
Advantages • Penetrates well• Makes tissue less
brittle• Thicker tissue
>1mm can be processed
• Non flammable
Disadvantages • Highly toxic due to
phosphogene gas• End point cannot
be determined• Used in well
ventilated room
Chloroform:•Commonest agent in routene use by manual methods because of its tolerance•Often used when processing specimens of CNS
![Page 34: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/34.jpg)
Advantages • Rapid clearing• Least hardening &
shrinkage• Less toxic• Excellent for tissues
such as skin, uterus, muscle & tendon
Disadvantages • Must be removed with
xylene before impregnation
• Expensive• Remanants may cause
difficulty in sectioning
Cedar wood oil:• Best reagent for research• Tissues can be left for longer period even for months without damage
![Page 35: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/35.jpg)
Methyl benzoate and methyl salicylate:• Slow acting and can be used when
double embedding techniques are required
• Moderate speed of action• Minimal distortion of tissue
Citrous fruit oils:• They are extracted from orange and
lemon• Nontoxic and miscible with water, so
they can be discharged through ordinary waste pipes thus avoiding the cost of disposal
![Page 36: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/36.jpg)
Universal solvents• Some fluids are capable of acting as
dehydrating agents and at the same time they are miscible with molten paraffin wax, thus avoiding intermediate clearing stageDioxane, 1:4 diethlene dioxide
- highly toxic therefore not used
Ethylene glycol monoethyl ether (cellosolve)
-less toxic, slow action & requires further investigation
![Page 37: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/37.jpg)
Recycling of processing fluids
• Distillation equipment is used• Advantages include
Reduced costRapid, efficientEliminates the risk of disposal of
toxic chemicals
![Page 38: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/38.jpg)
Impregnation/Infiltration
• Infiltration is the saturation of tissue cavities and cells by a supporting substance which is generally, but not always, the medium in which they are finally embedded
![Page 39: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/39.jpg)
Ideal requisites • Soluble in processing fluids• Suitable for sectioning and
ribboning• Molten between 30°C and 60°C• Translucent or transparent;
colourless• Stable, non toxic, odorless• Homogeneous• Capable of flattening after
ribboning• Easy to handle• Inexpensive
![Page 40: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/40.jpg)
Paraffin wax• Most popular due to ease with which
large number of tissue blocks may be processed in comparatively short times
• Staining presents fewer difficulties than other media
• Cheap, easy handling, inexpensive, wide range of melting point & provides quality section
• It can be used in different climatic regions
• Volume of wax should be about 25-30 times the volume of tissues
![Page 41: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/41.jpg)
Properties • It is a mixture of hydrocarbons
produced by sweating and pressing the residue to vacuum distilled crude oil.
• Melting point range is between 40-70°c, normally for routine use 54-58°c is satisfactory
• Higher the melting point of wax, harder the wax at any given temperature
• Plastic point governs the behaviour of the wax. Plastic point [at which crystalline rearrangement occurs] is 10°c below the melting point.
![Page 42: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/42.jpg)
Paraffin wax additives
• Plasticizers or other resin additives to provide desired hardness
• Substances added to paraffin are bees wax, rubber, ceresin, plastic polymers
• Additives with higher melting point than paraffin can make the tissue brittle
![Page 43: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/43.jpg)
Time of impregnation
• Duration & number of changes depends on:
• Size & type of the tissue• The clearing agent employed• Use of vaccum-embedding
oven
![Page 44: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/44.jpg)
Size and type of tissue:
Size:• Thicker the tissue, longer will be the
time required for wax to penetrate• Thick tissue will carry more of the
clearing agents, & hence requires more change of wax to remove it.
Type:• For dense tissue impregnation time is
twice that of soft tissues (liver and kidney)
E.g: Bone, skin, central nervous system.
![Page 45: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/45.jpg)
The clearing agents employed:
• Some clearing agents are replaced faster than others.
• Xylene, chloroform, toluene and food oils require two changes of wax. While cedarwood oil requires several changes
![Page 46: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/46.jpg)
Vacuum impregnation:• Normal paraffin wax impregnation with
two changes of wax takes over a period of 4 hours. By use of vacuum impregnation this time may be halved.
• This procedure not only speeds up impregnation but also rapidly remove air bubbles and clearing agents from the tissue
• The degree of vacuum should not exceed 500 mm of mercury
• Tissues benefited from this are lungs, muscles, spleen, decalcified bone, skin and central nervous system tissue.
![Page 47: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/47.jpg)
Methods of processing
Manual tissue processing
Automated tissue processing
![Page 48: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/48.jpg)
Manual tissue processing
Manual tissue processing has now largely been superseded by automatic tissue processing but there are occasion when it may be necessary to adopt this procedure.
These circumstances are– power failure or breakdown of a tissue processor– requirement for a non-standard processing
schedule like:• rapid processing of an urgent specimen • delicate material • very large or thick tissue blocks • hard, dense tissues (nitrocellulose
methods)
![Page 49: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/49.jpg)
Advantages • Flexibility of reagent selection,
conditions and schedule design to provide optimum processing for small batches of tissues.
• Exposure of tissues to the deleterious effects of some reagents can be carefully monitored and regulated through observation and precise timing
• Use of fluids on grounds of inflammability, volatility or cost would be unacceptable in automated techniques.
![Page 50: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/50.jpg)
Manual processing schedules
![Page 51: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/51.jpg)
![Page 52: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/52.jpg)
Automated tissue processing
• The basic principle for tissue processing requires the exchange of fluids using a series of solutions for a predetermined length of time in controlled environment
• Automated machines are most widely used to overcome the possibilities of human error and forgetfulness leading to changing of fluids at inconvenient times
![Page 53: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/53.jpg)
Types
Tissue-transfer processors
Fluid-transfer processors
Microwave tissue processors
![Page 54: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/54.jpg)
Tissue-transfer Processors
• These processors are characterised by the transfer of tissues, contained within a basket, through a series of stationary reagents arranged in-line or in a circular carousel plan
• The rotatory or carousel is the most common model of automatic tissue processor
• Fluid agitation is achieved by vertical oscillation or rotary motion of the tissue basket
![Page 55: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/55.jpg)
Fluid-transfer Processors
• In fluid-transfer units processing fluids are pumped to and from a retort in which the tissues remain stationary
• Depending upon the model these machines can process 100-300 cassettes at any one time
• Agitation is achieved by tidal action
![Page 56: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/56.jpg)
Processing Schedules
![Page 57: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/57.jpg)
Microwave processors• Rapid manual microwave-stimulated paraffin
wax processing gives excellent results compared to tissues processed by longer automated non-microwave methods
• Processing is undertaken in a dedicated microwave oven which is fitted with precise temperature control and timer, and an interlocked fume extraction system to preclude accidental solvent vapour ignition.
• Toxic and flammable solvent vapours generated during processing cannot always be adequately vented from these ovens and present an ignition hazard if the electrical system is unprotected
![Page 58: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/58.jpg)
Rapid Automated Processing
• The enclosed system machine have the facility to use vacuum and heating at all stage which can greatly increase the speed of processing.
• Spleen, muscle, skin, decalcified tissue and tissues containing blood clot to become unduly hardened if high temperature are used
• This can be minimised by using limited temperature during fixation, dehydration and clearing
![Page 59: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/59.jpg)
Techniques for increasing speed of processing:• The use of warm (40-50C) 45º C for
30 min, fixative to ensure that fixation is complete before commencing dehydration.
• Dehydration commencing at 95% alcohol stage
• The use of a fast acting clearing agents
• The use of a vacuum infiltration at all wax stage.
• Agitation at all stage even during fixation.
• The minimum of time at all the stage
![Page 60: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/60.jpg)
Conclusion
Producing quality slides for diagnosis is not an accident rather it essentially requires skills that are developed by continued practice & experience
![Page 61: 7th seminar-Tissue Processing & Embedding.pptx](https://reader033.vdocument.in/reader033/viewer/2022052318/577cc0611a28aba7118fe42e/html5/thumbnails/61.jpg)
To be conscious that you are ignorant is a great step to knowledge
- Sir Benzamin Disreli