Instrumentation

Desiccator function

air tight dish containing small beads responsible for removing excess moisture from the air

desiccator maintenance requirements and quality control

ensure that it has a tight seal, is cleaned properly, and replace the beads

desiccator clinical application

used for chemicals that absorb moisture from the air, which can cause them to degrade

freezer clinical use

using for storing tissue, concentrated antibodies, precut immunohistochemistry control slides, reagents, and buffer solutions

freezer maintenance and quality control

Do not have a freeze-thaw cycle, temperatures should be closely monitored and alarm systems in place

hydrometer function

measures the specific gravity of a liquid

hydrometer maintenance and quality control

ensure that the equipment is cleaned after each use, and that the mercury or lead shot is where it should be

hydrometer clinical use

Used for measuring the amount of water in the alcohols of the tissue processor

incubator clinical use

Set at body temperature for enzyme reactions, situ hybridization applications, some stains

incubator maintenance and quality control

temperature should be monitored daily and proper cleaning performed

laboratory glassware use

used to hold, mix, and measure reagents

borosilicate glass

high thermal resistance and is resistant to corrosion

low-actinic glass

dark brown to amber, designed to limit amount of light that enters the container

standard flint

less resistant to high temperatures and chemical attacks

graduated cylinders

used for exact measurements

beakers, coplin jars, and flasks

used to hold reagents

lab glassware maintenance and quality control

Make sure that bottles are tightly closed, glass is not chipped, and when measuring, make sure to measure from the bottom of the meniscus to ensure the proper volume is measured. Clean after use by rinsing 3 times with DI water, and then with cleaning chemicals, rinsed 3 times again, and left to dry upside down

pH meter clinical use

used for enzyme histochemistry techniques because most solutions require a specific pH before use

pH meter maintenance and quality control

Standardized using a standard solution close to the pH of the solution being tested, store electrodes properly according to the type

pipette clinical use

Used in immunochemistry for the dilution of antibodies

pipette maintenance and quality control

Use good micropipetting technique, never set pipette outside of limits (can cause it to uncalibrate), never hold pipette horizontally when it has liquids, and place pipette back in holder when not in use, calibrate pipette annually

Refrigerator clinical use

Used for storing reagents, buffers, tissue, enzyme histochemistry reagents, and diluted antibodies used in immunohistochemistry

refrigerator maintenance and quality control

temperature should be monitored daily and alarm systems should be in place

scale use

used for solution preparation and weighing dyes and chemicals

scale maintenance and quality control

wipe down equipment, tare before use, and make sure has 1-2mg sensitivity, calibrated annually

stir/hot plate use

used to thoroughly mix and heat reagents

stir/hot plate maintenance and quality control

Clean and decontaminate after use, ensure that the plate is warming and stir bars are working as intended

pH scale

measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14, 0 being acidic and 14 being basic

units of measurement for reagent preparation

grams and mL (microliters for histoimmunology)

resolving power

the ability to reveal fin detail or to discriminate between adjacent detail; 0.2 micrometers

parfocal

all objects will have the focal point in the same plane and magnification

micrometry

microscopic measurements

resolution

The optical ability to distinguish 2 objects a minimal distance apart as 2 objects

birefringence

transmitting light unequally in various directions

fluorescence

an optical phenomenon in which light of 1 wavelength is absorbed by a substance and almost instantly reemitted as light of a longer wavelength

ocular

viewing/magnifies 10x

arm

structural piece for carrying

course adjustment knob

course/large focus

fine adjustment knob

fine/small focus

base

stability/structure

rheostat

light intensity

condenser adjustment knob

moves condenser up and down

stage adjustment knob

moves the stage forwards/backwards and left to right

iris diaphragm

opens/closes light source

condenser

focuses/blends light onto specimen

objective

magnifies and resolves specimen

total magnification of a microscope

10 x objective lens magnifying power (10, 40, 60)

achromatic

corrected for 2 colors, red and blue

apochromatic

corrected for 3 colors and for other lens aberrations

light microscope principle

Light is aimed towards a condenser, which focuses the light through the object

the objective lens collects the light and magnifies the image

light microscope use

Quality monitoring in histology and for diagnostic histopathology practices

polarizing microscope principle

Uses vibrating light to visualize anisotropic samples with birefringent qualities

Has a polarizer between the light source and specimen, and an analyzer between the specimen and the eye

Birefringent components appear apple green in color

polarizing microscope use

Useful in specialized medical and industrial

Diagnosing amyloid stained with congo red

Identifying crystals such as talc, silica, and urates

phase contrast microscope principle

Light passes through transparent specimen slower that light that is uninfluenced

Wavelength has a phase shift

Transparent phase-plate in microscope intensified and translates the lift in light, causing it to be bright transparent object to stand out in contrast to the background

phase-contrast use

Can be used to study live organisms and other structures that may be destroyed in staining process (cell cycle)

Used to visualize specimen with transparent or colorless properties

dark-field microscope principle

Sample is illuminated with light that is mostly not collected by the objective lens

Light that is directly transmitted through the specimen is excluded due to direct illumination block

Bright object appears in midst of a dark background

dark-field microscope use

Used to visualize live, unstained samples or microorganisms (mostly bacteria)

Tissue culture or single-celled water-borne organism

fluorescent microscope

Uses a dual filter system

UV passes through excitation filter, excites fluorophores

Fluophores release light and passes through an emission or barrier filter, resulting in a distinct color

A dichromatic mirror also helps direct the appropriate wavelength for light

fluorescent microscope use

Used for situ hybridization that can be used to diagnose malignancy by enabling the quantification of select chromosomes present in a cell

Also visualize fluorescein Isothiocyanate in immunohistochemical staining

Auramine Rhodamine with acid fast bacilli

transmission electron microscope (TEM) principle

Electron beam passes through an ultrathin specimen

2D, black and white image with electron lucent (clear) and electron dense (dark) areas

TEM use

Useful for ultrastructure of an organism

scanning electron microscope (SEM) principle

Electrons from beam interact with sample's atoms producing info in forms of signals about the surface and composition of specimen

3D black and white image

SEM use

Useful for crystal structure or chemical analysis

purpose of oil immersion

decreases diffraction of light as it passes through the object

role of the computer and laboratory information system in histopathology

The LIS receives, processes, and stores information generated by lab process and often interfaces with additional institutional software and histology related equipment. Specimens are tracked by the system as they go through the laboratory.

importance of confidentiality

Confidentiality is important for every role in healthcare and is protected under HIPAA. This means that only those who are part of the care team for the patient should know details about the case. If you must share with someone else, like you need help with something and you need to ask someone, keep the information minimal and unidentifiable

define quality control

Creating a culture of quality and continuous improvement to ensure that the results are always high quality, and our patients can be properly cared for - this includes monitoring and maintaining the instruments we work with

cryostat function

A traditional rotary microtome encased in a cooling chamber to check fresh tissue while surgery is ongoing

Rapid results for a quick analysis by the pathologist

cryostat quality control

Temperature and the blade should be monitored

drying oven function

Removes excess water and helps attach the tissue to slide

20-30 minutes at 60 C or 2-4 degrees above paraffin melting point

drying oven quality control

Temperature should be carefully monitored

embedding center function

Used to orient and surround the processed tissue in a liquid embedding medium which is then solidified to create a tissue block

embedding center quality control

Monitor temperature of embedding paraffin, forceps must be kept clean

hood function

Used when working with hazardous chemicals to limit exposure to noxious fumes and vapors

hood quality control

Only effective when used properly, annual quality checks to ensure that air is being moved and filtered properly

Sash maintained at optimal operating high, keep glass panes closed when the sash is open, limit excessive clutter

microtome (rotary) and associated water bath function

Used to cut thin sections of tissue to be placed on a microscope slide for viewing

Water bath used to float ribbons of tissue for mounting onto a glass slide

microtome (rotary) and associated water bath quality control

Ensuring the angle of the blade is correct, checking the temperature of the water bath

paraffin vat function

Used to melt solidified paraffin pellets and store for future use

paraffin vat quality control

Temperature is critical and needs to be monitored

staining microwave function

Used during histochemical staining to heat solutions (acts as a catalyst)

staining microwave quality control

Temperatures should be controlled and radiation leakage monitored

Caution used when removing the heated solution

tissue processor function

Used along with fixation to preserve the morphology of tissue specimens for pathologic review and diagnosis

tissue processor quality control

Monitor temperature and adequate ventilation, ensure the alarm system is working, use a hydrometer to measure the water content of the alcohol

closed tissue processor

tissue remains stationary in retort while chemicals are transferred into the holding chamber

Less chemical exposure, but can't use certain chemicals (chloroform)

open tissue processor

tissue is transferred through a series of stationary chemicals

Allows for special processing techniques (such as a whole eye) and is gentler on the tissue

Higher risk of chemical exposure

microwave tissue processor

microwave technology to create friction, which warms the chemicals and rapidly preserves the tissue sample

Tissue should be closely monitored and safety checks for radiation leakage

how a microwave works to aid in the processing and staining of tissue

A microwave heats the tissue, removing the water through evaporation. It also acts as a catalyst for tissue staining

clinical freezing microtome principle

Tissue is frozen on a metal stage and a large blade is moved across the face of the tissue

Sections are then free floated for staining

clinical freezing microtome use

fresh tissue slides generated in 1-2 minutes

rotary microtome principle

Moves block up and down across a steel blade while advancing the block forward slowly with each manual turn

sliding microtome principle

The block is stationary while the blade moves across the surface of the tissue

sliding microtome use

Used to cut large paraffin or celloidin embedded tissue blocks

most commonly used in research

ultramicrotome principle

Embedded in a plastic embedding medium and uses diamond blades to cut ultrathin slices

ultramicrotome use

Used to cut sections for light and/or electron microscopy

vibrating microtome principle

Uses a vibrating blade to cut thin section of fixed or unfixed tissue samples

Vibration of blade requires less pressure than a stationary blade

vibrating microtome use

to cut fresh tissue

role of automation

Automation can be used for both quality control and for high volume laboratories. It is used in staining to ensure the timing and quality of the stains. It is used in coverslipping because of high volumes. It can also be used to decrease physical stress on technicians

preventative maintenance

cleaning machines, storing them properly, using them properly, and calling maintenance when machines are broken so you don't break them further

corrective maintenance

after an instrument is already broken, and is fixed retroactively

maintenance applications for HTs

Perform daily quality checks (especially for temperatures), calibrate instruments often to a known standard, use control samples with known values regularly, perform regulate maintenance on machines (cleaning, software updates, and repairs), and document all that was previously listed