Histology Lecture 1

Question 1

Histology bridges…

Answer 1

Physiology and Gross Anatomy

Question 2

4 main tissues in the body

Answer 2

Connective, epithelium, muscular, and neural

Question 3

3 types of microscopes

Answer 3

Light microscope, transmission electron microscope, and scanning electron microscope

Question 4

Light microscope

Answer 4

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.

Question 5

Transmission electron microscope

Answer 5

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

Question 6

Scanning electron microscope

Answer 6

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

Question 7

Stains

Answer 7

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

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

Question 8

Hematoxylin and Eosin Stain

Answer 8

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

Question 9

Silver Stain/Reticular Fiber stain

Answer 9

uses silver saltreticular fibers become blacksometimes a counterstain is used

Question 10

Masson’s Trichrome

Answer 10

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

Question 11

Periodic Acid-Schiff Stain

Answer 11

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

Question 12

Wright’s Stain

Answer 12

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

Question 13

Open-faced vs Close-faced Nucleus

Answer 13

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

Close-faced - not mitotically active; opaque

Question 14

Cell Inclusions

Answer 14

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

Question 15

Glycogen

Answer 15

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

Question 16

Lipid

Answer 16

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

Question 17

Crystals

Answer 17

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

Question 18

Pigments

Answer 18

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

Question 19

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

Answer 19

Lipid droplets and pigments

Question 20

Melanin

Answer 20

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)

Question 21

Hemosiderin

Answer 21

residue of RBC destruction (phagocytized)

Question 22

Lipofuscin

Answer 22

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