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