[Histonet] fixation-question

[Rittman, Barry R]

 Hi
Short answer due to time constraints.
See Pearse 1980.
1.	Formalin can be removed from tissues as evidenced by the
breaking of temporary bonds and reconstitution of tissue if fixation is
relatively short.

2. No. In general formalin reacts more rapidly if in acidic pH.

3. Acidic fixatives such as Carnoy generally give much better fixation
of nucleic acids than solutions such as formalin. With fixtives such as
Bouin's the nucleic acids are precipitated rendering them more readily
stained.
Hope that this helps.
Barry

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Gudrun
Lang
Sent: Monday, August 06, 2007 1:18 PM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] fixation-question

Hi to all fixation-experts,

I've found in the literature some controversy statements about
formaldehyd-fixation and want your help, what is the
up-do-date-knowledge.

-          Formaldehyd can/cannot be washed out of fixed tissue.

-          Formaldehyd fixates slower in more acid pH; uncharched
aminogroups react better than protonated with formaldehyd. And these
groups should be uncharged in neutral pH.

-          Nuclear chromatin is fixed only by acid fixatives.

 

What is your opinion on these statements?

 

Regards

Gudrun Lang