[Histonet] PAP stains

[John Kiernan]

Charles,  What do you mean by "dark nuclei"? Are you asking about the normal colour for the method, or about something you have not seen before that looks wrong?  Also, what is "PAP stain"?


If "PAP stain" means Papanicoloau, the nuclear stain is Mayer's haemalum. This is a progressive stain; you may need to shorten the time.


If "PAP stain" means peroxidase-antiperoxidase (unlabelled antibody-enzyme complex for amplifying detection of HRP-tagged secondary antibodies in immunohistochemistry), nuclei will be dark (usually brown) if they contain the antigen sought by the primary antibody. Nuclear staining might also be a false-positive artifact; if so, it would be present in the simplest of the routine controls (omission of primary antibody).  Dark nuclei might also be due to a nuclear counterstain that is too strong. The counterstain should be done in a contrasting colour. Usually it is a progressive haemalum (blue) to contrast with the oxidation product of DAB (brown).


Is this a Papanicoloau question or an immunohistochemistry question?  Does "PAP stain" have a third meaning?


John Kiernan

= = =

________________________________
From: Charles Riley via Histonet <histonet at lists.utsouthwestern.edu>
Sent: 19 March 2019 14:17
To: Histo List
Subject: [Histonet] PAP stains

What causes dark nuclei in the PAP stain.

--

Charles Riley BS  HT, HTL(ASCP)CM

Histopathology Coordinator/ Mohs
_______________________________________________
Histonet mailing list
Histonet at lists.utsouthwestern.edu
http://lists.utsouthwestern.edu/mailman/listinfo/histonet