Laboratory: Intro to Histology Flashcards
Study of the tissues of the body and how these issues are arranged to constitute organs
Histology
Two Interacting Components of Tissues
Extracellular Matrix
Cells
Supports the cells and the fluid that transports
nutrients to the cells and carries away their catabolites and secretory products.
Extracellular Matrix
Produce the ECM and are also influenced and
sometimes controlled by matrix molecules.
Cells
The technical field of using microscopes to view samples & objects that cannot be seen with the unaided eye (objects that are not within the resolution range of the normal
eye).
Microscopy
An instrument that magnifies an image and allows visualization of greater detail than is possible with the unaided eye.
Microscope
Tasks of Microscope
Magnification
Resolution
Contrast
Produce a magnified image of the specimen
Magnification
Separate the details in the image
Resolution
Render the details visible to the eye, camera, or imaging device
Contrast
Father of Microscopy
Anton von Leeuwenhoek
Meaning of Mikros
Small
Meaning of skopein
To look
Most commonly used in the laboratory
Compound Light Microscope
Bright Field Microscope
For illumination of specimen
Light Source
Focus the beam of light at the level of the specimen
Condenser
On which the slide or other specimen is placed. The flat platform where the slide is placed for examination.
Stage
Gather the light that has passed through the specimen. The purpose of this is to increase or decrease magnification.
Objective Lens
Through which the image formed by the objective lens may be examined directly. Located at the top of microscope that the viewer looks through to observe the specimen. It typically magnifies the image by 10x.
Ocular Lens or Eyepiece
Provides support for the microscope
Base
Supports and holds the magnifying and adjustment
system
Arm
Located directly under the stage and hold the
condenser and diaphragm
Substage
Permits movement of the stage while holding the slide in the phase of focus
Mechanical Stage
Magnification Powers of Objectives
Scanning (4x)
Low (10x)
High (40x)
Oil Immersion (100x)
Normal tube length
160mm
Uses a lens system that produces visible images from transparent objects can be used with living, cultured cells. Used to examine living cells and tissues and is used extensively to examine unstained semi-thin (approximately 0.5um) sections of plastic-embedded tissue
Phase Contrast Microscope
Allows quantification of
tissue mass
Interference Microscope
Uses Nomarski optics, which produces an image of living cells with a more apparent 3D aspect
Differential Interference Microscope
Only light that has been scattered or diffracted by structures in the specimen reaches the objective. Equipped with a special condenser that illuminates the specimen with strong, oblique light.
Dark Field Microscope
Makes use of the ability of certain molecules to
fluoresce under ultraviolet light
Fluorescence Microscope
Allows visualization of a biologic specimen in three dimensions. Combines components of light optical microscope with a scanning system to dissect a specimen optically.
Confocal Microscope
Small point of high-intensity light
Laser
Allows the recognition of stained or unstained structures made of highly organized subunits such as birefringent crystals
Polarizing Microscope
Microscopes that uses beam of electrons (instead of a beam of light) and electromagnets (instead of glass lenses)
Electron Microscope
Imaging system that permits resolution around 3nm, allowing isolated particles magnified as much as 400,000 times
Transmission Electron Microscope
Provides a high-resolution view of the surfaces of the cells, tissues and organs. Easy to interpret since they present a three-dimensional image.
Scanning Electron Microscope
One of the most powerful tools for studying the surface topography at molecular and atomic resolution. Most useful for biological studies
Atomic Force Microscope
It is the digital procedure that is an alternative to the examination of glass slides using a light microscope
Virtual Microscope
Steps in Preparation of Tissue for Examination
- Fixation (formalin)
- Dehydration (ethanol)
- Clearing (xylene)
- Infiltration (paraffin)
- Embedding (paraffin)
- Sectioning (rotary microscope)
- Staining (H&E)
- Mounting (resin)
Stops cell metabolism
Prevents autolysis
Kills pathogenic microorganisms
Fixation
Most commonly used fixative
10% neutral-buffered
form (NBF-phosphate buffer) formalin
A 37-40% (saturated) aqueous solution of formaldehyde gas
Formalin
10% formalin means
4% aqueous formaldehyde solution
Water has to be removed by
Immersion in graded (ascending) concentrations of a dehydrating agent
Most commonly used dehydrating agent
Ethanol at 70%, 90% & 100% concentrations
For delicate tissues,
dehydration is started at
30% or 50% dilution
Clearing agents that act as an intermediary between the dehydrating agent & the embedding agent
Xylene
Toluene
Temperature for infiltration
52-60 degrees Celsius
Prevents distortion of tissue structure during microtomy
Embedding
Removal of excess wax to expose the tissue for sectioning on a microtome
Trimming
Shape to be achieved in trimming
Truncated Pyramid
Size of thin sections
5-15μm
Thickness of ribbon sections to be cut
3-5 μm
Free end of the ribbon is held by
Fine-pointed forceps
Teasing needle
The other end is detached from the microtome knife with
Sable or Camel Hair Brush
Temperature of the bath should be __ less than the melting point of the paraffin
10 degrees Celsius
After 30 seconds, sections are picked up onto
Clean, albuminized (adhesive) slides
Universal size of standard slides
76x25mm, with a thickness of 1.0-1.2mm
Overnight drying temperature
37 degrees Celsius
Negatively charged, has an affinity to basic dye termed as Basophilic
Nucleic Acid
Positively charged, has an affinity to acidic dye, termed as Acidophilic
Cytoplasm/Organelles/Proteins
Most commonly used staining method
Hematoxylin & eosin (H&E) stains
Mounting medium
DPX resin
Container for tissue embedding
Cassette
