On Mon, 1 May 2000, Jeannette wrote:

> Have looked high & low for the formula that includes Bismark Brown for
> EA-50. Thanks. Jeannette leydelab@erols.com

According to Humason's Animal Tissue Techniques, Papanicolau's
solution known as "Eosin-azure 36 (EA-36 or EA-50)" is:

 Light green SF yellowish (0.5g in 100 ml 95% alcohol): 45 ml
 Bismarck brown (0.5 g in 100 ml 95% alcohol):          10 ml
 Phosphotungstic acid:                                 0.2 g
 Lithium carbonate (saturated, in water):              1 drop
 Eosin Y (0.5 g in 100 ml 95% alcohol):                 45 ml

It seems a crazy mixture! The name is odd too, because it
does not contain any dye with "azure" in its name. References
are given to 4 papers (1942, 1947, 1954, 1957) by G.N.Papanicolau.

Modern Pap stains are somewhat more rationally formulated, and don't
include the bismarck brown or that one drop of Li2CO3. See Boon and
Drijver 1986 "Routine Cytological Staining Techniques" New York:
Elsevier, or other recent texts. All the dyes used in Pap staining
are available "certified." If you want to keep the preparations
for a long time, use fast green FCF instead of light green SF. Their
staining properties and colours are the same but the latter fades
with long storage. 

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1