Anita,

These acidophilic needle or lance shaped crystals will appear red and slightly opaque on H&E stains examined by brightfield microscopy.

Perhaps I should have said that these crystals exhibit anisotropism!
The terms anisotropic and birefringent are commonly interchanged.
Birefringence is observed by means of a polarizing microscope.
With crossed polarizers certain objects, such as Charcot-Leyden crystals, will exhibit anisotropism/birefringence and will appear bright on a dark background. When the specimen is rotated these objects will blink on and off approximately every 90 degrees.

When a birefringent object is transilluminated by plane polarized light, each light ray is split into two part-rays. The ordinary ray passes through the object in a straight line(i.e. as in isotropic objects), whereas the second ray is laterally displaced(i.e. as in anisotropic objects). These two part rays differ in polarization direction by 90 degrees. They also differ in their velocity of propogation. That is, they have different refractive indices, hence the object producing them is birefringent.

Bryan

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From:   ajennings@unmc.edu[SMTP:ajennings@unmc.edu]
Sent:   April 22, 2002 7:31 AM
Cc:     Histonet@pathology.swmed.edu
Subject:        Charcot-Leyden crystals-birefringence?




Not sure if birefringence is appropriate description, or if it is just my
definition of "birefringment". the crystals that we observed were opague
and stained red, not what I considered "normal" crystal appearance. anyone
have any help with this? I know the dictionary definition and I dont want
to get into index of refraction etc. (or I could ask on the confocal
server) <smile> I just want clarification of the term when is comes to
observing crystals under the scope and a description of what is observed.
i.e. transparent etc.
thanks
anita

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