You did not say what the specimen is nor the size??? Total fixation is
important here, and leaving it in 70% over the weekend with a fresh change
could guarantee this even in a dessicator under vacuum. Do you also take
bone all the way through clearing, in xylene for PMMA on processor? I
presume you do unless you use MMA monomer (not processor friendly) for this
step.   I would err on side of longer dehydration/clearing (yours is
equivalent to overnight per change) if you have any doubt and the bone is
really large/dense.  It ties up  processor, but it is so nice to have one
available to do the work. 


Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology - Marsh Lab
Montana State University - Bozeman
19th and Lincoln St
Bozeman MT 59717-3610

406 994-6367 (lab with voice mail)
406 994-4303 (FAX)

email: gcallis@montana.edu