I have had a similar(ish) problem with my small skin biopsies for immunofluorescence.  They come to me in transport media, and I would wash them in my DIF wash solution before freezing and embedding.  The problem I discovered was that if there was significant amounts of the wash solution left on the outside of the specimen, this solution formed a "weak link" when sectioning, and it was impossible to get a section - all I would get was (as you say) a section of OCT with a hole in it.  Do your muscle biopsies come to you in saline?  If so, you may be experiencing a similar effect to me!

Best of luck
Aidan, New Zealand.


_____________________________________
a i d a n   c   s c h u r r
 section head, histology
  department of pathology
hutt valley health
high street, lower hutt
wellington
new zealand
telephone ++64 4 5709173
facsimile ++64 4 5709214

>>> Lynn Gardner <lynn-gardner@uiowa.edu> 4:43:46 a.m. Friday, 12 January 2001 >>>
Dear Histonetters,

We experienced an interesting problem when working with some muscle tissue
the other day and was wondering if anyone out there has experienced it and
if so how did they correct for it.

We frozen some muscle tissue in isopentane cooled in liquid nitrogen to a
temperature of -160. The tissue looked compeletly frozen when removed. We
immediately placed the tissue in a vial and put in the -80 freezer. We
embedded in OCT and tried to cut and all we got was a big hole in the OCT.
The tissue seemed as though it was not frozen. Any idea of what happened??
We have done this with other tissue and it worked fine. We know the freezer
did not thaw out. So we are at a loss. 

I would appreciate any input! Thanks in advance gang!
Lynn Gardner, HT(ASCP)