Toluidine Blue

Joanne Dannenhoffer Joanne.M.Dannenhoffer at
Wed Oct 8 19:34:42 EST 1997


As an anatomist who has benefitted greatly from this newsgroup.....

As I understand it, Toluidine Blue in sodium borate has a different pH and
therefore stains differently.  On fresh tissue, at optimal concentration
and pH it will stain primary walls a pinkish-purple and secondary walls
blue or blue-green.   In addition, unless the stain is filtered, there is a
lot of particulate matter.  I generally just use 0.05% aqueous TBO although
I have several recipes (see below) in addition to the one posted.
Additionally, I try to avoid using the sodium borate in class if I can.

In introductory labs,  we use it with celery because of the collenchyma.
(They can relate to this because they all know about the "fibers" they get
when eating celery.)   Unstained celery, shows the thickened primary walls
of the collenchyma as glistening white and because they are very thick,
students believe they are cells with secondary wall.  After staining with
toluidine blue, the walls are clearly pink and because you can see the
middle lamella as darker purple, it's easy to see the walls are unevenly
thickened.   In contrast, the tracheary elements stain a deep blue or blue
green.  The reason I like TBO is because the students can then several
different cell types in the celery.  


TBO recipes and references:
0.05% in 0.1M phosphate buffer at pH 6.8   O'Brien, Feder, and McCully 1964
 Polychromatic staining of plant cell walls by Toluidine Blue O
Protoplasma 59:368
0.05% in pH 4-6 citrate-phosphate buffer  Sakai  1973  Simple method for
differential staining of paraffin embedded plant material using TBO
Stain Technology 45:247
(This works great!  You can stain right through the paraffin and then just
remove the paraffin with xylene and mount the coverslip.)

Can plants with mycorrhizal associations and no root hairs, produce root
hairs in the absence of the mycorrhizal fungus?

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