I'm glad John Kiernan had the formula for the Engel-Cunningham frozen section 
trichrome stain on hand. 

I tried to set up that stain for human skeletal muscle frozen sections in 
1969, when I was a fellow in the pathology department at Johns Hopkins. I was 
unable to get the stain to work, and I finally visited Guy Cunningham, the 
histotechnologist in W. King Engel's muscle pathology laboratory at the National 
Institutes of Health. They let me look at their procedure in detail. I noted that 
they were using a true Harris hematoxylin - oxidized with mercuric oxide - 
while we were using an iodate-oxidized hematoxylin, home-made (John R. Baker's 
formula) in our research lab. I quickly purloined some Harris hematoxylin from 
the cytopathology service, and after that the stain worked fine. I added 
mercuric chloride to our standard hematoxylin, and that worked too.

That was 35 years ago. You couldn't buy hematoxylin with mercury in it 
nowadays, and you wouldn't want to make it either. There are still commercial 
hematoxylins labeled Harris hematoxylin, which I think now means "any alum 
hematoxylin our marketing department wants to call Harris hematoxylin".

I'm curious to know what's become of this problem.

Bob Richmond
former Samurai Pathologist
now at Gaston Memorial Hospital, Gastonia NC
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