LESSON 2: FIXATION Flashcards
What are the 2 purposes of Fixation?
- Preservation: primary purpose
- Protection: secondary purpose
capable of forming cross-links between proteins
Fixative agents
becomes part of the cross-link itself
Additive
facilitates the removal of water in order for cross-links to form
Non-Additive
Routine manual, automated, microscopy temp?
20-22C
40C
0-4C
▪ Formalin at 60 oC: very urgent biopsies
▪ Formalin at 100 oC:____________
Diagnosis of tuberculosis
Cover with several layers of gauze
Air-filled Lungs
✓ Dilate with cotton soaked in fixative
✓ Completely open specimen
Hollow Organs
✓ Fix first before sampling
✓ Suspended by a cord tied under the Circle of Willis
✓ Intravascular perfusion using Ringer’s lactate
Brain
✓ Fixed whole
✓ Inject formol-alcohol
Eyes
washed out with running water overnight and immersed in 4% aq. phenol solution for 1-3 days
Lendrum’s Method
✓ Stretched with sutures on each end
✓ Laid flat in a moist filter paper
Muscles
permit general microscopic study of tissue structures and normal intercellular relationship of tissues
Microanatomical Fixatives
preserve specific cellular components
Cytological Fixatives
✓ preserve nuclear structures
✓ contain glacial HAc
▪ high affinity to nuclear chromatin
▪ destroys mitochondria and Golgi bodies
✓ contain glacial HAc
Nuclear Fixatives:
