[Histonet] HT HistoDeck question frozen section fixation

[Heimrich, Elizabeth]

Hi all,  Since the key to the question lies in Optimal Fixation, the answer to this question is A, and it is taken right out of the Histotechnology self-instructional text 2nd edition pg 98. (See note)
Under Frozen Sections

I've included a procedure I have used successfully in the past.  It differs from the text book by the addition of the acid hematin pigment removal steps

1.        Cut the frozen section and fix in 37%-40% FORMALDEHYDE for 20 sec

2.       Cut frozen section and place slides in 37% Formaldehyde (unbuffered) for 30sec -1min (have kept them in formaldehyde longer~20min with no adverse events

3.       Treat for acid hematin pigment with saturated alcoholic picric acid (Polyscientific  R&D cat# S2357) for 20-30mins

4.       Rinse in 95% EtOH 2x

5.       70% EtOH 1x

6.       Running tap H20 until all yellow pigment has been removed

7.       Rinse in dH2O and stain with H&E protocol

Carson's NOTE:  Many labs use acetone or alcohol for frozen section fixation; however Conc. Formaldehyde yields morphologic preservation as seen in permanent sections.
 Hope this helps.
Beth


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