Medical Applications fo Tissue Processing and Examination Flashcards
Step 1 Fixation
Chemical: Formalin, glutaraldehyde
Purpose: preservation of normal tissue architecture after death, fixatives coagulate or precipitate proteins, renders the structures resistant to further processing
Step 2 dehydration
chemical- graded series from 50-100% of ethanol
purpose- remove water from the tissue specimen and replace it with alcohol
step 3 clearing
chemical- xylene
purpose- prepares the tissue for the embedding medium, paraffin
step 4 embedding
chemical- paraffin
purpose- tissue is infiltrated with paraffin so that it is hard enough to section
step 5 sectioning
no chemical
purpose- tissue is cut into thin sections with a microtone
step 6- mounting
no chemical
purpose- cut paraffin section is placed on a glass microscope slide
step 7- staining
chemical- various chemicals used
purpose- to impart contrast to tissue structures so that they may be distinguished upon microscopic observation
Hematoxylin
affinity- RNA, DNA, ribosomes, rER
color- blue
basic dye
Eosin
affinity- secretory vesicles, sER, lysosomes, mitochondria, and type I collagen
color- pink
acid dye
Feulgen reaction
affinity- DNA
color- magenta
Mallory triple
affinity- nuclei, muscle, collagen, hyaline cartilage color- nuclei= red muscle= red to orange collagen= blue hyaline cartilage= blue
PAS reaction
affinity- carbohydrates
color- magenta
Osmic acid
affinity- lipids
color- black
Verhoeff
affinity- elastic fibers
color- black
Silver methods
affinity- intermediate filaments or nerve cells, glial cells, and reticular fibers
color- black
Trypan blue
affinity- macrophages
color- blue
Prussian blue
affinity- hemosiderin, ferric iron
color- blue
Nissl
affinity- ribosomes
color- blue
Iron hematoxylin
affinity- nuclear elements, chromosomes, mitochondria, centrioles, and muscle striation
color- dark blue to black
**Metachromasia
given stain imparts different colors to the tissue, shifts the labeling of the dye molecule based on density, not all cells show this, seen in granulated mast cells that are imparted by heparin, the toludine blue dye in the mast cells is denser in some parts than other (gives a blue appearance to a red appearance)
**PAS
used in diagnosis of kidney disease, glycogen storage disease, and AAT
AAT- is misfolded and accumulates in the rER, used for thickened basement membranes, can see accumulations of PAS positive proteins
**Mallory Triple
trichrome stain, cocktail, used in diagnosis of pulmonary fibrosis, collagen is shown as blue, shoes an abnormal accumulation of collagen causing lung inflation to be restricted, pattern of breathing becomes shallow and rapid, imparts different colors to diff tissue structures based on molecular distribution
**Congo Red
identify extracellular accumulation deposits of amyloid, can determine if there are amyloid deposits in the wall of a blood vessel, amyloid= pathological accumulation of protein in tissue, ordinary light it will appear red, in polarized light it will appear red-green
**Frozen tissue samples
sections are thicker and fine detail is lost compared to a routine tissue sample
