Mosson Fontana - Melanin Stain

Question 1

What is the

Classification:
Target tissue component:
Mechanism of staining:
Staining principle:
Positive controls:

for masson fontana

Answer 1

Classification: Pigment stain
Target tissue component: Argentaffin substances (melanin, argentaffin granules)
Mechanism of staining: silver impregnation
Staining principle: Argentaffin metallic impregnation
Positive controls: skin (melanin), intestine (argentaffin granules)

Question 2

What is the staining principle of masson fontana

Answer 2

Argentaffin tissue components like melanin can bind to silver from a silver solution reducing the ions to visible metallic silver without an external reducer

Question 3

Purpose of Masson Fontana

Answer 3

detection of Argentaffin tissue components like melanin, argentaffin granules, neurosecretory granules

stains carcinoid tumors and melanoma

Question 4

how does Masson Fontana work

Answer 4

oxidizer Iodine suppresses sulphydryl and tryrosine groups so phenolic rings are left to bind with silver ions from the methenamine silver solution

for a negative control - use K permang to bleach melanin = confirming its presence like in PASD DONE BEFORE STAINING

positive QC (unbleached), negative QC (bleached) and patients X2 slides each (bleached and unbleached)

Question 5

What material is needed for masson fontana

Answer 5

formalin fixed tissues
water bath between 40-50
Microwave method like JMS and GMS
Chemically cleaned glassware

Question 6

What is the impregnating solution

Answer 6

Fontanas ammonican silver solution

first drops will turn solution black
-drop until solution is clear
-titrate with AGNO3 so solution is cloudy

Question 7

What is the bleaching step done with

Answer 7

30 mins in Kpermang

rinse, Oxalic acid , wash in RTW