Exam 1: Tissue Processing Flashcards
Fixation
Step 1
Use Formalin Glutaraldehyde; preservation of normal tissue after death
Dehydration
Step 2
Use Graded series of ethanol; remove water from tissue and replace with alcohol
Clearing
Step 3
Use Xylene; prepare tissue for embedding medium
Embedding
Step 4
Use Paraffin; tissue is infiltrated with paraffin so that it is hard enough to section
Sectioning
Step 5
Cut tissue into thin sections with a microtome
Mounting
Step 6
Place sections on a glass microscope slide
Staining
Step 7
Use various chemicals to impart contrast to tissue structures
Acid dyes
negative charge
Basic dyes
positive charge
Acidophilic
tissue structures that have a positive charge and attract negatively charged dye
Basophilic
tissue that has a negative charge and attracts positive dye
Metachromasia
stain imparts different colors to tissue
Hematoxylin
Blue
Attracts to RNA, DNA, ribosomes, and rER
Use for coagulative necrosis
Eosin
pink
attracts to secretory vesicles, sER, lysosomes, mitochondria, and type 1 collagen
Use for coagulative necrosis
Feulgen reaction
Magenta
attracts to DNA
can be used to demonstrate nuclear changes in cancer
Mallory triple
Nuclei - red Muscle - red to orange Collagen - blue Hyaline cartilage - blue Can be used to highlight fibrosis
PAS reaction
Magenta
Carbohydrates
can be used to see thickened basement membranes in kidney disease, glycogen storage diseases, and alpha1-antitrypsin deficiency in liver cells (hepatocytes)
Osmic acid
lipids black
Verhoeff
elastic fibers black
Marfan syndrome
Silver methods
Intermediate filaments of nerve cells, glial cells, and reticular fibers black
Trypan blue
macrophages blue
Prussian blue
Hemosiderin (ferric iron) blue
Can be used to demonstrate excessive iron accumulation in hemochromatosis
Nissl
Ribosomes blue
Iron hematoxylin
nuclear elements, chromosomes, mitochondria, centrioles, and muscle striation dark blue to black
Congo Red
identify extracellular depositis of amyloid
Immunocytochemistry
uses an antibody tagged with a marker directed to a specific antigen
Direct method is less sensitive than indirect method (more antibodies bind to indirect method)
In situ hybridization
Uses complementary nucleic acid probes to specifically identify a nuclei acid sequence
Can be used to identify a cell infected with a virus or specific genes
