Re: again blueing sections (& Haema-what?)
|From:||"J. A. Kiernan" <email@example.com> (by way of histonet)|
You raise a couple of questions, so here are a couple of answers.
The first (long) is about names and is, IMHO, correct. The second
answer (short) is merely a little more speculation about the
deposits on your slides.
On Wed, 13 Sep 2000, Heike Grabsch wrote:
> - I have already seen precipitates coming directly from haemalaun (or is
> it called haematoxylin? please forgive me for my ignorance),
Haematoxylin is the compound you dissolve; it is colourless when
pure. It is oxidized to haematein, which is yellow and can form
coloured complexes with many metals. When the metal is aluminium,
the solution is called a haemalum. It is commonly the colour of
red wine, but may be purple, depending on the formulation. (pH and
amount of excess aluminium ions affect the colour.)
Solutions such as Ehrlich's, Delafield's, Mayer's, Harris's, Gill's
etc are all haemalums, but they are regularly wrongly named as
"haematoxylins." With other metals the dye is also haematein, not
haematoxylin, but everyone says "Weigert's haematoxylin",
"phosphotungstic acid-haematoxylin" etc, and many live with the
illusion that the H in H&E is for haematoxylin rather than haemalum.
Next paragraph is small-print stuff.
The system of names is complicated by variations in spelling. The
haem- is simplified to hem- in American English. In German, many
informal chemical names end in -ine rather than -in or -ein, and
the ending -ine is used for many compounds that in English
should end in -in. The French are as bad, with a propensity to
make all the words end in -ine. These suffixes are chemically
significant in English usage, and modern writers from Continental
Europe now follow the same principles, but plenty of anomalous
spellings are still frequently seen because of uncritical use of
words taken from German or French into English. The Colour Index
(CI) itself uses the archaic German "haematine" for haematein,
probably retained un-noticed for 50 years, but modern German
writers on dye chemistry (Heinrich Zollinger is pre-eminent)
use the convention of -ine for bases (amines), -ein for compounds
in which unsaturation is significant, and -in for uncharged or
anionic dyes. Haematoxylin and haematein are uncharged (but can
form anions). Eosin and phloxin are also anionic dyes, so it is
wrong to put an -e on the end of either. Thionine is a basic
(cationic) dye, so it should never be spelled as "thionin,"
and the same is true of all dyes with "fuchsine" or "rosaniline"
as parts of their names. Even acid fuchsine (an anionic dye)
gets a terminal -e because it is formed by sulphonation of a
basic parent compound.
Returning to haemat- Don't ever confuse any of these
compounds with haemoglobin and some of the products of its
degradation, such as acid haematin (formalin pigment). There
is an excellent stain known as Baker's acid haematein that
uses chromium as the metal component. It is nearly 60 years
old and its histochemistry was sorted out nearly 40 years ago.
It displays structures rich in choline-containing phospholipids,
including mitochondria and myelin sheaths of axons.
End of small-print stuff.
> (BioGenex) as chromogen, rinse in dist. water, 90 sec Mayer's,
Could the rinse in water after buffered AEC be insufficient?
If some phosphate buffer carries over into the haemalum
there could be precipitation of aluminium phosphate, with
attachment of haematein to the Al ions.
John A. Kiernan,
Department of Anatomy & Cell Biology,
The University of Western Ontario,
LONDON, Canada N6A 5C1
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