histopathology

1. Histotechnology
And equipments

2. Histotechnology
• The technique of processing the tissue submitted for
histopathological study until the preparation of the stained section
on a glass microscopic slide ready for study is known as
Histotechnology.

3. Steps
• Preparation of the tissue
• Processing of the tissue
• Preparation of the section
• Staining
• mounting

4. Laboratory equipments
• Tissue processor
• Moulds , Embedding tissue with cassettes
• Tissue embedding centre
• Microtome
• Paraffin bath
• Automatic knife sharpener
• Tissue floatation bath
• Slide warmer
• Automated slide stainer
• Automated coverslipper
• Cryostat
• Microscope
• Storage cabinet

5. Tissue processor
• Tissue processor are compact and sturdy instrument designed
with latest technology for complete automated dehydration
and filtration of human tissue up to final fixing in wax.

7. Moulds, embedding tissue cassettes
• Embedding of tissue is done in molten wax.
• Wax blocks can be conventionally prepared using metallic L (
Leuckhart’s ) moulds.
• Nowadays plastic moulds of different colours for are also available.
• Same plastic moulds with detachable plastic covers can be used for
the twin purpose of tissue capsule as well as moulds for blocking.

8. • The moulds are placed over a smooth surfaced glass slide tile.
• Molten wax is poured into the cavity in the moulds.
• The processed tissue pieces are put into wax with number tag
and examining surface facing downward.
•
• Wax is allowed to solidify.

10. Tissue embedding centre
• Embedding and blocking can also be performed in a special
equipment called embedding centre.
• It has a wax reservoir, heated area for steel moulds, wax
dispenser and separate hot and cold plate for embedding and
blocking.

12. Microtome
• Microtome is a tool used to cut extremely thin slices of
material, known as sections.
• Microtomes are used in microscopy, allowing for preparation
of samples for observation under transmitted light or electron
radiation.

14. Tissue Floatation Bath
• This is designed to assist with the handling of paraffin wax
samples in histopathology.
• It is essentially a hot distilled water floating out bath that allow
for the meticulous manipulation and location of paraffin wax
section on glass slide.

16. Automated slide stainer

17. Automated coverslipper system

18. Frozen Section
• When a fresh tissue is rapidly frozen, the matter within the
tissue turns into ice; in this state the tissue is firm. The ice
acting as embedding medium.
• Therefore , sections are produced without the use of
dehydrating solution, clearing agents and wax embedding.

20. Drying oven or Hot plate
• Small drying ovens are now available, incorporating a fan,
espically designed for drying tissue sections.
• A hot plate may be used instead of a drying oven.

21. Forceps and squirrel hair brush
• These tools are needed for handling sections during cutting,
and for removing folds and crease on the section during
floating out in water bath.

22. Clean slides
• For routine work, 76x25mm slides that are 1.0-1.2 mm thick
are usually preferred because they do not break easily.

23. Risk management and safety in the laboratory
• Protect the hands and forearms by wearing either gloves and a
laboratory coat or suitable long gloves to avoid contact of the
toxic material with the skin.
• Wash hands frequently throughout the day and before leaving
the lab.
• Procedures involving volatile toxic substances and those
involving solid or liquid toxic substances that may result in the
generation of aerosols should be conducted in a fume hood or
other suitable containment device.
• The laboratory workplace should be well-ventilated, clean and

24. • Do not wear shorts, sandals, or open-toed shoes in laboratory.
• Minors or personal pets are not permitted in the laboratory.
• Secure any dangling jewelry, restrain loose clothing, and tie
back long hair that might get caught in equipment before
starting work.
• Use of cell phones and music headphones should be avoided
while working in the lab.They can be distracting and can
increase the potential for an accident to occur. They can also
become contaminated if handled while working with
hazardous materials.

25. • Eye wash station, safety shower and first aid kits should be
standard facilities in a laboratory. Fire extinguishers,
emergency shower systems, emergency eye washers, first aid,
emergency blankets, and hoods must be checked monthly.
• To avoid the unnecessary purchase of chemical materials, a
detailed list of chemical materials must be prepared. Only a
minimum amount of volatile chemicals must be kept in the
laboratory.
• Chemical material should be stored and safely secured where
there is sufficient ventilation. Combustible chemical material

26. • All chemical material must be labeled with the name,
characteristics, danger level, and precautionary measures.
• Avoid handling the sharp ends of instruments. Use forceps or
other tools to remove sharp instruments from baskets and
autoclaves. Workers should use appropriate hand protection
when hands are exposed to hazards such as cuts, lacerations or
thermal burns.
• Laboratory accidents must be documented and investigated
with incident reports and industrial accident reports. Obtain
medical advice (first aid officer, doctor, poisons information

27. Types of hazards
• Most hazards encountered fall into three main categories:
1.chemical,
2.physical or
3.biological.

28. Chemical Hazards
• Cleaning agents and disinfectants, drugs, anesthetic gases,
solvents, paints, and compressed gases are examples of
chemical hazards.
• Potential exposures to chemical hazards can occur both during
use and with poor storage.
• The potential for harm or injury could be significant if
chemicals are misused or mishandled.
• The “lab standard” applies to the laboratory use of chemicals
and mandates written in the Standard Operating Procedures
(SOPs) that address the particular hazards and precautions

29. • Every chemical should be labeled with certain basic
information, including:
• Chemical name and, if a mixture, names of all ingredients
• Manufacturer's name and address if purchased commercially,
or
• name of person making the reagent
• Date purchased or made
• Expiration date,
• if known, Hazard warnings and safety procedures.

30. Types of chemicals
• Irritants are chemicals that cause reversible inflammatory effects at
the site of contact with living tissue, especially the skin, eyes and
respiratory passages.
• Corrosive chemicals cause destruction or irreversible alterations
when exposed to living tissue, or destroy animate surfaces
(generally metal).
• Sensitizers cause allergic reactions in some exposed workers, not
just in hypersensitive individuals. Sensitization may occur at work
because of the high exposure level.
• Carcinogens are substances that induce tumors. Eg. chloroform,
chromic acid, formaldehyde, nickel chloride and potassium
dichromate. Carcinogenic dyes- auramine, basic fuchsin, and any

31. Physical Hazards
• The most obvious physical hazards are slips and falls from
working in wet locations and the ergonomic hazards of lifting,
pushing, pulling, and repetitive tasks.
• Other physical hazards often unnoticed are electrical,
mechanical, acoustic, or thermal in nature. Ignoring these can
have potentially serious consequences.
• Clearly labeled puncture proof and leak proof containers must
be used for “sharps”. The container must be replaced when
three-fourths full to prevent over-filling.
• Discard any broken, cracked, or chipped glassware.

32. Electrical Hazards
• In the laboratory, workers may be exposed to electrical hazards
including electric shock, arc blasts, electrocution, fires and
explosions.
• Potential exposures to electrical hazards can result from faulty
electrical equipment/instrumentation or wiring, damaged
receptacles and connectors, or unsafe work practices.
• Damaged electrical cords can lead to possible shocks or
electrocutions.

33. Biological Hazards
• Biohazards include infectious agents and their toxins as well as
contaminated solutions, specimens or objects. Allergens, are
one of the most important health hazards, yet they are
frequently overlooked.
• Molds and fungi produce and release millions of spores small
enough to be air, water, or insect borne which may have
negative effects on human health including allergic reactions,
asthma, and other respiratory problems

34. • Pathologists, histotechnologists and technicians may be
exposed to a certain level of risk when handling and processing
potentially infectious specimen through inhalation of aerosols,
contact with non-intact skin and contact with mucous
membranes (eyes, nose, mouth).
• Fresh tissue and body fluids must always be considered
potentially infectious, and grossing of specimen has the
highest risk of all histological activities.
• Fixed specimens have a much less risk because nearly all
infectious agents are deactivated by histological fixation,

35. Thank you