histology lab quiz 0

Histology

Study of the anatomy of cells and tissues of body by using microscopy

Distance maxes for eye, light microscope, electron microscope

Eye: 0.1 mm

Light: 0.1 um

Electron: 0.1 nm

Simple microscope features

Image, object, lens

• virtual image

Compound microscope

Light source, condenser lens, specimen, objective lens, ocular lens

• inverted image

• Need staining, image is not the actual color

• 2D

Magnification levels

Ocular: 10x

Low: 4X, 40X total mag.

medium: 10X, 100X total

High: 40x, 400X total

Oil: 100X, 1000X total

Stereo microscope

3D, reflected image, light source on top

Electron microscope vs light microscope

Light uses photons but electron uses electrons to show (darker means high electron density)

• electron has shorter wavelengths, larger magnification, difficult to prepare, has a vacuum, and is expensive

Transmission electron microscope

2D, transmitted electrons, black and white

• Compound microscope is comparative

Scanning electron microscope

3D, section not necessary, electrons scan over surface of sample

Staining

Only needed for compound microscopes

• general and special

H&E staining (general)

Basic dye: hematoxylin, blue, positive, basic

• affinity for nuclei (DNA is negative) and RER (basophilic structures)

Acidic dye: eosin, red, negative, acidic

• affinity for positive proteins such as mitochondria (acidophilic structures)

Special staining (4)

PAS: stains glycogen (liver)

Trichrome: massons trichrome stains collagen fibers

H&E: mix of blue and red (blue parts are basophilia and red are eosinophilia)

silver stains: stains neurons and neuroglia, stains reticular fibers