EXAMINATION OF FRESH TISSUE Flashcards
is the microscopic study of the normal tissues of the body
Histology
is the microscopic study of tissues affected by disease.
histopathology
The procedures adopted for the preparation of material for such studies (histopathology) are known as
histologic or histopathologic techniques
The tissues are usually obtained during (3)
surgery, biopsy, or autopsy
The following surgical procedures are usually performed to obtain the specific-types of tissue that are submitted to a histology laboratory for processing:
Fine needle aspiration
core needle biopsy
incisional biopsy
excisional biopsy
Punch biopsy
Shave biopsy
Curettings
is the simplest, least invasive test and uses the smallest needle to simply remove cells from the area of abnormality.
This is not always adequate to obtain a diagnosis, depending on the area to be biopsied.
Fine needle aspiration
removes not only cells, but also a small amount of the surrounding tissue. This provides additional information to assist in the examination of the lesion
core needle biopsy
takes out even more surrounding tissue.
It takes out some of the abnormality, but not all.
The doctor will slice into the lesion and remove only a portion of it.
If the lesion is found to be cancerous, further surgery may be needed to remove or excise the entire lesion.
incisional biopsy
generally removes the entire area in question.
excisional biopsy
is considered the primary technique for obtaining diagnostic full-thickness skin specimens.
It requires basic general surgical and suture-tying skills and is easy to learn.
The technique involves the use of a circular blade that is rotated down through the epidermis and dermis, and into the subcutaneous fat, yielding a 3- to 4mm cylindrical core of tissue sample.
Punch biopsy
- where small fragments of tissue are “shaved” from a surface (usually skin).
Shave biopsy
- where tissue is scooped or spooned to remove tissue or growths from body cavity such as endometrium or cervical canal.
Curettings
Methods of Fresh Tissue Examination
- Teasing or dissociation
- Squash preparation (crushing)
- Smear preparation
- Touch preparation
3 types of smear preparation
Streaking
Spreading
Pull-apart
– is a process whereby a selected tissue specimen is immersed in isotonic salt solution such as normal saline or Ringer’s solution in a petri dish or watch glass, carefully dissected with a needle and separated by direct or zigzag spread using an applicator stick.
Teasing or Dissociation
is a process whereby small pieces of tissue (not more than one mm. in diameter) are placed in a microscopic slide and forcibly compressed with another slide or with a cover glass.
If necessary, a supravital stain may be placed at the junction of the slide and the cover glass, and allowed to be absorbed by the tissue through capillary attraction.
Squash Preparation (Crushing)
– The method of preparing the _____ differs depending on the nature of the material to be examined.
As a general rule, _____ are made either by spreading the selected portion of the specimen over the surface of the slide with a platinum loop.
Alternatively, an apposition ____ can be made using a second slide to obtain a relatively uniform distribution of secretion.
Smear Preparation
is useful for preparing smears of thick secretions such as serous fluids, concentrated sputum, enzymatic lavage samples from the gastrointestinal tract, and blood smears.
Smearing
This technique is especially useful in cytological examinations, particularly for cancer diagnosis.
Smearing
-With an applicator stick or a platinum loop, the material is rapidly and gently applied in a direct or zigzag line throughout the slide, attempting to obtain a relatively uniform distribution of secretion.
Too thin or too thick smears have to be avoided, since they make the tissues unsuitable for examination.
Streaking
- A selected portion of the material is transferred to a clean slide and gently spread into a moderately thick film by teasing the mucous strands apart with an applicator stick.
Spreading
It is a little more tedious than streaking, but has the advantage of maintaining cellular interrelationships of the material to be examined.
It is especially recommended for smear preparations of fresh sputum and bronchial aspirates, and also for thick mucoid secretions.
Spreading
– This is done by placing a drop of secretion or sediment upon one slide and facing it to another clean slide.
The material disperses evenly over the surface of the two slides.
Slight movement of the two slides in opposite directions may be necessary to initiate the flow of materials.
The two slides are then pulled apart with a single uninterrupted motion, and the specimen is placed under the microscope for immediate examination, or applied with vital stains.
Pull-Apart
– This is a special method of smear preparation whereby the surface of a freshly cut piece of tissue is brought into contact and pressed on to the surface of a clean glass slide, allowing the cells to be transferred directly to the slide for examination by Phase Contrast microscopy or staining for light microscopic study.
It has an added advantage in that the cells may be examined without destroying their intercellular relationship.
Touch Preparation (Impression Smear)
Touch preparation aka
Impression smear
Squash preparation aka
Crushing
• Done by carefully separating very thin tissue slices with dissecting needles.
TEASING OR DISSOCIATION
Teasing
Stain:
Methylene Blue (optional)
Teasing advantages & disadvantages
Advantages:
Permitting the cells to be examined in the living state.
Disadvantages:
Preparations are not permanent
Done by simply crushing small pieces of tissue between two glass slides or between a glass slide and a cover slip
SQUASH PREPARATION OR CRUSHING
SQUASH PREPARATION OR CRUSHING
Tissue size:
not more the 1 mm in diameter
SQUASH PREPARATION OR CRUSHING
Stain
Supravital Stain (optional)
• Method of choice for examining sediments or samples in liquid/fluid form.
SMEAR PREPARATION
Smear prep
Samples:
serous fluid
concentrated sputum
enzymatic lavage sample from Gl tract
Made either by spreading the selected portion of the specimen over the surface of the slide with a platinum loop
Smear prep
Smear prep
Encompasses the ff. methods of examination:
Pull-apart
Streaking
Spreading
Touch Preparation
• Rapid diagnosis.
• Uses freezing microtome or cryostat.
FROZEN SECTION (CRYOSECTION)
Cryostat
______ (size), frozen rapidly to about ______ (temp)
• Embedded in a gel like medium consisting of polyethylene glycol and polyvinyl alcohol
5-10um
-20 to -30°C
TEASING OR DISSOCIATION PROCEDURE
- From the frozen block of tissue, cut several small, thin slices of tissue
- Immerse the tissue slices in a petri dish filled with saline solution (NSS)
- Using a dissecting needle, carefully tease the tissue slices until they unfold and spread out.
- Carefully mount a teased slice on a slide and cover it with a coverslip
SQUASH PREPARATION OR CRUSHING PROCEDURE
From the 4th step of the previous procedure:
1. Add 1-2 drops of methylene blue stain directly on the tissue slice on the glass slide.
The tissue specimen previously immersed with the NSS is utilized.
- Cover the stained tissue with a cover slip or another glass slide.
- Applying enough pressure to crush the tissue flat.
- Label your slide with your name, group number and section and submit it to your instructor.
SMEAR PREPARATION PROCEDURE
Smear Preparation.
• Centrifuge body fluid samples and decant the supernatant.
• Avoid making smears that are too thin or too thick since this will render your smears unsuitable for examination.
Streaking
- Pour a small amount of the sediments on one end of a clean glass slide.
- Using an applicator stick, streak the sediments in a straight or zigzag line throughout the remaining length of the slide. If a wire loop is used instead, collect a loopful of the material and smear the material on the slide. A relatively uniform distribution of the material should be obtained.Cover it with a cover slip.
- Label your slide with your name, group number and section and submit it to your instructor.
Spreading
- Transfer a small amount of the sediments on one end of a clean glass slide.
- Using an applicator stick, spread the sediments throughout the slide (similar to how butter is spread on bread). Another technique is to place the drop of sediments at the center of the slide.
Then with a circular motion, gently spread it into a moderately thick film - Label your slide with your name, group number and section and submit it to your instructor.
Pull-apart
- Place a drop of the sediments at one end of a glass slide
- Cover it with the end of another glass slide. Allow the sediments to spread evenly between the attached surfaces of the two slides.
- With a single, uninterrupted motion, pull the two slides apart in opposite directions. Cover the smear with a cover slip.
- Label your slide with your name, group number and section and submit it to your instructor.
Touch Preparation
- Retrieve the block of tissue from the first procedure (See Teasing p.18). Cut the block in half, exposing a
trasher surrace - Allow the freshly cut surface to come in contact with the surface of a clean glass slide. Apply gentle pressure, allowing the cells to be transferred directly to the slide. Cover the smear with a cover slip
- Label your slide with your name, group number and section and submit it to your instructor.
