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1

Histology bridges...

Physiology and Gross Anatomy

2

4 main tissues in the body

Connective, epithelium, muscular, and neural

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3 types of microscopes

Light microscope, transmission electron microscope, and scanning electron microscope

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Light microscope

A compound microscope that is composed of a specific arrangement of lenses that permit a high magnification and good resolution of the tissues being viewed.

5

Transmission electron microscope

It uses much thinner sections compared with light microscopy and requires heavy metal precipitation techniques rather than water-soluble stains to stain tissues

High magnification

Stream of electrons pass through thin specimen, is refined, and then hits the screen producing a negative image

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Scanning electron microscope

provides a 3D image of the specimenviews the surface of the specimen so electrons do not pass through the specimen

7

Stains

More common: hematoxylin and eosin, and silver stain (reticular fiber stain)

Less common: Masson's trichrome, periodic acid-Schiff stain, and Wright's stain

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Hematoxylin and Eosin Stain

Most common (what we will be looking at 95% of the time)

Hematoxylin is a basic dye that stains acidic (basophilic) structures (DNA, RNA, etc.) purple

Eosin is an acidic dye that stains basic (acidophilic) structures from pink to orange

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Silver Stain/Reticular Fiber stain

uses silver saltreticular fibers become blacksometimes a counterstain is used

10

Masson's Trichrome

3 color sating protocol - connective tissue is blue, nuclei and muscle are dark red/purple, and cytoplasm is red/pink

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Periodic Acid-Schiff Stain

basement membrane (collagen fiber), glycogen, and other carbohydrates stain magentanuclei stains blue

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Wright's Stain

Common stain w/ blood:
nuclei - bluish purple
cytoplasm - light pink/grey
RBCs - pink
neutrophil granule - clear
eosiniphil granules - bright red/orange
basophil granules - deep purple/violet
platelet granule - red/purple

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Open-faced vs Close-faced Nucleus

Open-faced - mitotically active; space needed for DNA to unwind

Close-faced - not mitotically active; opaque

14

Cell Inclusions

nonliving components of cells that do not possess metabolic activity and are not bounded by membranes

what a cell does not directly need to live

most common: glycogen, lipid droplets, crystals and pigments

15

Glycogen

a type of cellular inclusion

common form of glucose in animals and is especially abundant in cells of the muscle and the liver

important energy source for those cells

16

Lipid

Triglycerides in storage form is a typical type of cellular inclusion especially as adipocytes but also other cell types including hepatocytes

source of energy and short carbon chains by cell in membrane and hormone synthesis

along with pigments = most common inclusion body seen under H&E Staining

17

Crystals

Type of cellular inclusion

believed to be crystalline forms of certain proteins common in sertolli and Leydig cells of testes

crystal inclusions found in large cells with sarcoidosis and consisting mainly of calcium oxalate as well as soon calcium carbonatecells do not "like" crystals bc they grow on top of eachother

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Pigments

various compounds found in the cell that can serve a protective function (melanin), marks cells age or exposure to oxidative stress (lipofuscin)

along w/ lipid droplets = most commonly seen cellular inclusion with H&E Staining

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What are the 2 cellular inclusions seen most commonly with H&E Staining

Lipid droplets and pigments

20

Melanin

Most common biological pigment

produced by melanocytes (derived from neural crest)

migrate during development to specific places (esp the integument but also some parts of the nervous system)

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Hemosiderin

residue of RBC destruction (phagocytized)

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Lipofuscin

yellow-brown granules containing residues of lysosomal digestion

considered sign of aging or "wear and tear" pigmentfound in liver, kidney, hear muscle, adrenals and nerve cells