PRELIM: INTRODUCTION TO HISTOLOGY Flashcards
Levels of Cellular Organization
Cells, Tissue, Organ, Organ System, Oragnism
is the study of the tissues of the
body and how these tissues are arranged to constitute organs.
HISTOLOGY
group cells specialized to carry an
interrelated functions and their associated extracellular matrix.
Tissues
Tissues are made up of interacting components??
Cells and Extracellular Matrix (ECM)
Cells + Extracellular Matrix (ECM) = _____
Tissues
Provide support to the cells transport nutrients and eliminate wastes.
Extracellular Matrix (ECM)
Extracellular Matrix is composed of many kinds of???
Ground Substance and Fibers
What are the Extracellular Matrix in the tissue??
Ground Substance
Protein Fibers
Collagen Fibers
Elastic Fibers
What are the resident cells in the tissue??
Mesenchymal cell
Macrophage
Adipocyte
Fibroblast
The contents of the ECM may affect the function of the cells. True or false
True
To provide tissues, one must prepare thin and translucent histological sections or tissue slices that can be studied with the aid of a microscope.
PREPARATION OF TISSUE SLIDES
STEPS IN TISSUE PROCESSING:
Routine
Fixation
Dehydration
Clearing
Infiltration and Embedding
Trimming and Cleaning
Staining
STEPS IN TISSUE PROCESSING: For hard/calcified tissue
Fixation
Decalcification
Dehydration
Clearing
Infiltration and Embedding
Trimming and Sectioning
Staining
Since cellular decomposition begins
immediately after the death of a human/patient, tissues must be fixed to the cells to prevent alterations in their structure through decomposition.
(1) Avoid tissue destruction by digestive enzymes (autolysis) or through bacterial degradation.
(2) Terminate cell metabolism
(3) Preserve the structure and molecular composition,
(4) Kill pathogenic microorganisms such as bacteria, fungi and viruses.
(5) Hardens the tissue by cross-linking or denaturing proteins
Fixation
Commonly used fixative is
Formalin
Fixation
- Formann
- 10% _________
- 75% __________
Neutral Buffered Formalin, Formalin
Only done in specimens such as bone and calcified tissues.
- Purpose: Removal of calcium and lime salts; done after fixation and before dehydration and impregnation, calcium might interfere with accurate evaluation and examination.
- Significances: Facilitate normal cutting of tissue in sectioning.
Decalcification
Hard/Calcified Tissues:
- Bone
- Teeth
- Tuberculous lungs
- Atherosclerotic blood vessels
- Done by successively bathing the specimen in a mixture of ethanol and water from 70% to 100% (increasing concentration of alcohol)
- Alcohol removes water from the tissue
Dehydration
best dehydrant because it is fast
acting, mixes with water and many organic solvents, and penetrates tissues easily.
Not poisonous and not very expensive
Clear, colorless, flammable
Ethanol
Resident Cells
Mesenchymal cell
Macrophage
Adipocyte
Fibroblast
The contents of the ECM may affect the function of the cells. T or F?
True
PREPARATION OF TISSUE SLIDES
- To provide tissues, one must prepare _____________ that can be studied with the aid of a
microscope.
thin and translucent histological sections or tissue slices
What are the types of tissue processing?
Routine and For hard/calcified tissues
Removal of dehydrating agent by immersing the specimen in the solvent that the alcohol and
embedding medium is MISCIBLE.
- Makes tissue ‘’translucent’’ or transparent, hence the term _______
Clearing
Removal of dehydrating agent by immersing the specimen in the solvent that the alcohol and
embedding medium is MISCIBLE.
- Makes tissue ‘’translucent’’ or transparent, hence the term _______
Clearing
most commonly used clearing agent.
Xylene
______________
- After the clearing procedure, the tissue is placed in ________ in an oven set at ________.
- The heat causes the clearing agent toevaporate so that the tissue will be filled up with the paraffin.
- The tissue and paraffin will harden after removal from oven.
INFILTRATION AND EMBEDDING
melted paraffin
52-60 degree Celsius
- makes use of plastic solution which hardens tissue by cross-linking polymers.
- Eliminates the need to use oven andparaffin; little tissue distortion.
plastic resins
- After the specimen is hardened, it is trimmed into appropriately sized blocks.
CUTTING AND SECTIONING
is the removal of excess.
Cutting/Trimming
is done with the aid of a microtome.
sectioning
Cutting:
Sectioning:
steel knife
microtome
- Since paraffin is colorless, staining is a must.
Staining
Before staining, the following should be done:
- Removal of paraffin by xylol or toluol.
- Rehydration of tissue by descending concentration of alcohol.
Tissue with negative charges/acids are readily stained with dyes _______
Tissue = Acidic (-) to Basic dyes
Basophilic
Tissues with positive charges are stained with acidic dyes ________
Tissue = Basic (+) to Acidic dye
Acidophilic
Tissue with negative charges/acids are readily stained with dyes – BASOPHILIC, stained???
Nucleus/Nucleic Acid
Tissues with positive charges are stained with acidic dyes – ACIDOPHILIC, stained???
Mitochondria, cytoplasm, collagen
Most commonly used stain in histology
Hematoxylin and Eosin
basic dye; usually stains nucleus and RNA containing portion of cytoplasm.
Hematoxylin
acidic dye; usually stains cytoplasmic components and collagen
Eosin
Chemical stains:
Feulgen Reaction
Periodic-Acid Schiff
Sudan Black
Feulgen reaction – ________
Periodic-acid Schiff – _______
Sudan Black – _______
DNA
CARBOHYDRATES
LIPIDS
____________
- Placing cut sections on a slide with adhesives such as ________
- The last procedure in the series that ends with a permanent histological preparation on the table, after the staining.
MOUNTING
pinene or acrylic resins
a solution in which the specimen is embedded, generally under a cover slide.
MOUNTING MEDIUM
a solution in which the specimen is embedded, generally under a cover slide.
MOUNTING MEDIUM
- Fixation is done rapid freezing.
- Compressed carbon dioxide is emitted.
- Sectioning is done through cryostat, a refrigerated compartment containing microtome.
- Method is rapid.
- Routinely done in the hospital to study specimens during surgery.
- Lipids and enzymes are best preserved in this method.
FROZEN SECTIONS (for emergency surgery)