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From:"J. A. Kiernan" <>
To:Jo-Ann Bader <>
Date:Thu, 21 Oct 1999 13:29:57 -0400 (EDT)
Content-Type:TEXT/PLAIN; charset=US-ASCII

On Thu, 21 Oct 1999, Jo-Ann Bader wrote:

> I am looking for a stain specifically for mitocondria on paraffin sections.
> Is there such a thing?

  Yes indeed. Mitochondria were discovered by staining them
  in paraffin sections, and methods are given even in modern
  techniques books. I haven't tried all the methods, but have
  seen mitochondria using Baker's acid-haematein (a histochemical
  method for choline-containing phospholipids) and with Bensley's
  copper-haematoxylin, a traditional method. More ordinary dyes 
  will also stain mitochondria, but not selectively enough to
  see them properly. The most colourful selective method is
  said to be Altmann's aniline-acid fuchsine-picric acid, but
  I've never tried that one.

  Mitochondria can be stained only if they have been properly
  fixed before embedding. A mitochondrion is mostly membrane, so
  it's necessary to make the phospholipids insoluble before
  dehydration, clearing and embedding. This can be done by a
  treatment with osmium tetroxide or potassium dichromate (or
  both) after primary fixation in neutral buffered formaldehyde,
  with or without added glutaraldehyde. Helly's fluid also
  preserves mitochondria. The traditional fixatives for cytoplasm
  and organelles are unbuffered mixtures of OsO4 with K2Cr2O7,
  used on very tiny pieces of tissue. The sections need to be
  thin - 4 mu or less.

  The selective stains for mitochondria also colour red blood
  cells and myelin sheaths, but these do not cause confusion.

  It's good to hear that there's still a demand for traditional
  staining methods for mitochondria.

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

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