Hi,
You have probably exhausted these resources already, but just in case: See if you can find some med students willing to ccoperate; they have access and work odd hours (check some hang-outs near the local med school hospital). Also, prop managers at local live theater houses may have suggestions. If you are in NYC, LA, or Vancouver, there are prop renting businesses that could set you up in a minute.
Several years ago for a film class, I was teamed up with a med student who lived in an apt on the second floor above the local morgue. We ended up doing a piece entitled, Report From The Medical Examiner, that was largely shot "downstairs." (The medical examiners and people in charge worked normal hours unless there was "business" so we had free run of the place) There were ample frozen corpses and stuff in jars in the vicinity, but we kept it in good taste and got high marks on our finished film from the audience at a major open screeening attended by the public.
Good luck on your project!
REGARDS ... TOM 8)