I'm trying to embed and section mouse cochleas that have been immunoreacted
en bloc for BrdU with DAB as the chromagen.  The soft tissues of the cochlea
were separated from the bony structures, leaving a soft tissue spiral
containing the organ of Corti.

During processing for Epon-Araldite for 5 micron sections for light
microscopy (without osmium and using increasing concentrations of aqueous
acetone as the dehydrant), it appears as if the chromagen was lost (no
labeled cells were seen) and a purple/grey background was left behind.
Whole mounts immunoreacted at the same time retained an amber coloring with
dark brown-labeled nuclei.

Does anyone have any hints as to what happened here or what we can do in the
future to retain the labeling throughout plastic processing.  I've done this
embedding in the past with the same type of tissue (but still in the bony
labyrinth) and had no problems.

Thank you,

Jaclynn M. Lett, Research Assistant
jlett@cid.wustl.edu

Faye and Carl Simons Center for Biology of Hearing and Deafness
Central Institute for the Deaf
4560 Clayton Avenue
St. Louis, MO  63110

voice:  314.977.0257     fax:  314.977.0030