Intro/ Paraffin Technique

Gross anatomy

deals on the structures that can be observed by direct examination, palpation or dissection

microscopic anatomy

concerns the structures not visible by the naked eye and which requires a microscope to do so

histos

greek term for web

logos

greek term of study

tissu

french word for texture and weave

Marie FX Bichat

French Gross anatomist and Physician who introduced histology to medical sciences in the 18th century

Artifacts in tissue sections

must also be considered during tissue slide examination which includes stain precipitates, tissue folds, cracks, space or separation, knife marks, vacuoles/bubbles.

matchbox

Size of tissue to be collected

Fixatives

denature the protein contents and inactivate the enzymes of the tissue thereby rendering an almost in vivo condition

common simple fixative

Formaldehyde, picric acid, osmic acid, mercuric chloride, and acetone

10% NBF

commonly used fixative

depends on the size

Length of fixation of the tissue

100mL Formalin, Water 900mL, 4 g/L NaH2PO4, 6.5 g/L Na2HPO4

10% Neutral Buffered Formalin ingredients

Alcohol is not miscible with the paraffin embedding medium

The reason why alcohol should be removed

Xylene

the most commonly used clearing agent

tissue ribbons

forms from the cutting of tissue block into thin sections ( 5-7 microns) with the aid of a microtome

Deparaffinization

removal of paraffin from the tissue sections by immersion to xylene

Rehydration

introduction of water to deparaffinized sections through decreasing concentrations of alcohol (100-70%) to water in preparation to staining

Hematoxylin and Eosin Stain

routinely used for Staining with acid/base dyesis

Basic dye Hematoxylin

react with the acidic components of the cell, the nucleus which stains blue

Acidic dye Eosin

react to the basic cellular components of the cell, the cytoplasm that colors pink to red