INTRO TO HISTOLOGY Flashcards
What is histology?
The study of tissues of the body and how these tissues are arranged to constitute organs
WHAT IS Osmic acid, osmium tetroxide AND FOR WHAT IS USED?
ITS USED FOR LIPIDS IN GENERAL STAIN BLACK
Two Components of Tissues
Cells and Extracellular Matrix
Fixation
Small pieces of tissue are placed in solutions of chemicals that preserve by cross-linking proteins and inactivating degradative enzymes.
what are some examples of solutions for fixation?
Neutral buffered formalin and bouin fluid
Dehydration
Tissue is transferred through a series of increasingly concentrated alcohol solutions, ending in 100%, which removes all water. Removing water allows us to see
Clearing
Alcohol is removed in xylene in which both alcohol and paraffin are miscible
Infiltration
The tissue is placed in melted paraffin until it becomes completely saturated with this substance
Embedding
The paraffin-infiltrated tissue is placed in a small mold with melted paraffin and allowed to harden. If its going to be seen in EM it has to be resin instead of paraffin
Microtome
An instrument used to slice embedded tissues for light microscopy, 5-10micrometers
How dyes stain tissues?
more or less selectively behaving like acids or bases, forming puentes de sales electroestaticos.
what is the most common dye used?
Hematoxylin and eosin
How long could take a tissue prep?
It can take from 12 hrs to 2 days.
basophilic components
Cell components, such as nucleic acids, that have a net negative charge (anionic) and stain more readily with basic dyes
WHAT ELEMENTS DISPLAY BASOPHILIA? (BASIC LOVING)
HETEROCHROMATIN NUCLEI CYTOPLASMIC COMPONENTS- IONIZED PHOSPHATE IN RIBOSOMAL RNA EXTRACELLULAR MATERIALS LIKE COMPLEX CARBS
WHAT ARE Acidophilic components?
Cationic cell components, such as proteins with many ionized amino groups, that have an affinity for acidic dyes
WHAT ARE EXAMPLES OF ACIDIC COMPONENTS?
NUCLEIC ACIDS, DNA, SULFATE GROUP AND CARBOXYLIC GROUPS
Basic dyes
Tienen carga positiva por lo que se unen a cosas con carga negativa (componentes anionicos)
Ejemplos de basic dyes
Toluidine blue, alcian blue, methylene blue, hematoxylin
Acid dyes
tienen carga negativa por lo que se unen a cosas con cargas positivas Eosin, orange G, acid fuchsin
WHAT IS ACIDOPHILIA? OR EOSINOFILIA?
LIKES ACID DYE
H&E Stain
Hematoxylin stains DNA and other acidic structures dark blue or purple, and eosin stains other cytoplasmic components and collagen pink
PAS reaction
Periodic acid-Schiff reagent reacts with aldehyde residues on sugars to produce a purple or magenta color; stains polysaccharides and glycoproteins 1. GLYCOGEN 2. MUCUS 3. BASEMENT MEMBRANE 4. RETICULAR FIBERS IN CONNECTIVE TISSUE
Three lenses of a light microscope
Condenser, objective lens, eyepiece
what is the maximal resolving power of light microscopy?
0.2 micrometers. Smaller than this it cant be seen.
application of fluorescence microscopy
antibodies labed with fluorescnet compounds are important for inmunohistologic staining.
Magnification of light microscope
Objective lens x Ocular lens
Resolving power
The smallest distance between two particles at which they can be seen as separate objects
Fluorescence microscopy
Tissue sections are irradiated with UV light, and they emit light in the visible portion of the spectrum
types of light microscopy staining
- ones that differentiate between acidic and basic components of cell 2. specialized stains that differentiate fibrous components 3. metallic salts that precipitate on tissues, creating metal deposits
STAINS WITH EOSIN ELASTIN STAINS– CYTOPLASMIC STAINS– MUSCLES-
ELASTIN STAINS– GLASSY RED COLLAGEN STAINS- PINK MUSCLES- PINK
The Golgi stain is particularly good at revealing
NEURONAL FIBERS
Toluidine blue stain
A BASIC METACHROMATIC DYE WITH HIGH AFFINITY FOR ACIDIC TISSUE COMPONENTS
MASSON STAIN IS USED FOR…
CONNECTIVE TISSUE NUCLEI AND OTHER BASIC LIKING ARE STAINED RED
Phase- contrast microscopy
Uses a lens system that produces visible images from transparent objects, and, importantly, can be used with living, cultured cells; based on principle of differential refractive indices darker or larger in relation to each other
WHAT COLOR COLLAGEN STAINS WITH MASSON STAIN?
GREEN OR BLUE
DESCRIBE WRIGHT/ GIEMA STAIN
ITS USED TO IDENTIFY TYPES OF BLOOD CELLS.
WHAT COLOR ERYTHROCYTES STAIN WITH GIEMSA DYE?
PINK
WHAT COLOR PLATELETS STAINS WITH GIEMSA DYE?
LIGHT BLUE
Differential interference microscopy
Uses Nomarski optics, produces images of living cells with a more apparent 3D aspect
Confocal microscopy
Achieves high resolution and sharp focus by using a small pinpoint of high-intensity light and a plate with a pinhole aperture in front of the image detector
Polarizing microscopy
Allows the recognition of stained or unstained structures made of highly organized subunits; the oriented macromolecules rotate the axis of light between two polarizers like collagen, cellulose, actin, microtubules
Birefringence
The ability to rotate the direction of vibration of polarized light; a feature of crystalline substances or highly oriented molecules such as cellulose, collagen, micro tubules, and actin filaments
Transmission Electron Microscopy
Permits resolution around 3 nm; creates a greyscale image where the shade depends on whether electrons readily passed through the sample (brighter) or whether they were absorbed or deflected (darker). Cut with diamonds
Scanning Electron Microscopy
Provides high resolution view of the surfaces of cells, tissues, and organs; surface of specimen is dried and sprayed with very fine coating of heavy metal ( gold) that deflects the electron beam; black and white image
Autoradiography
A method of localizing newly synthesized macromolecules (DNA, RNA, protein, glycoproteins, polysaccharides) in cells or tissue sections; radiolabeled molecules react with AgBr crystals to produce dark spots in images
Enzyme Histochemistry
A method for localizing cellular structures using a specific enzymatic activity present in those structures
Phalloidin
Interacts strongly with actin
Protein A
Binds to immunoglobulin molecules and can be used to locate naturally occurring or applied antibodies bound to cell structures
Lectins
Proteins or glycoproteins that bind to carbohydrates with high affinity and specificity
Direct immunocytochemistry
Uses an antibody made against the tissue protein of interest and tagged directly with a label
Indirect immunocytochemistry
Uses a primary antibody made against the protein of interest and a labeled secondary antibody made in another species against the primary antibody
In situ hybridization (ISH)
Labeled cDNA that is complementary to a specific gene or nuclei acid sequence of interest is applied to a sample and the complementary sequences hybridize into double stranded nucleic acid
glycogen
free polysaccharide in animal cells
glycoprotein
have carbohydrate group attached to polypeptide chain. has short branched chains of sugars (oligosaccharides).
glycosaminoglycans
(GAGs) anionic unbranched long-chain polysaccharides containing aminated sugars.
proteoglycans
a compound consisting of a protein bonded to glycosaminoglycan groups, present especially in connective tissue.
enzyme digestion
pretreatment of a tissue section with an enzyme that specifically digests one substrate
counterstain
single stain that is applied separately to allow better recognition of nuclei and other structures
metal impregnation techniques
using silver slats solutions to visualize certain ECM fibers and specific cellular elements in nervous tissue
Cryofracture (freeze etching)
techniques that allow TEM study of cells without fixation or embedding.
primary cell culture
came straight from the organism
immunohistochemistry
highly specific interaction between molecules between antigen and antibodies.
What are antibodies?
An antibody, also known as an immunoglobulin, is a large, Y-shaped protein produced mainly by plasma cells that is used by the immune system to neutralize pathogens such as bacteria and viruses
What is an antigen?
a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies.
What are polyclonal antibodies?
different groups of lymphocytes in the injected animal recognize different parts of protein x and each clone produces an antibody against that part. each capable of binding a different region of protein x .
What are monoclonal antibody
Monoclonal antibodies are antibodies that are made by identical immune cells that are all clones of a unique parent cell. Monoclonal antibodies can have monovalent affinity, in that they bind to the same epitope.
what is hybridization
the specific binding between two single strands of nucleic acid, which occurs under appropriate conditions if the strands are complementary.
what are artifacts
spaces and precipitates that are not normally present in the living tissue and must be recognized
