For the best preservation of tissue morphology, we recommend that the thickness of the tissue for routine work be between 0.3 and 0.5 cm. To accommodate the embedding cassettes we ask that the other two dimensions not exceed 3.0 by 2.5 cm. Fixation alters tissue by stabilizing protein so that it is resistant to further change, a fixative changes soluble cell components into insoluble substances so that those substances are not lost during subsequent processing steps. For routine tissue fixation a fresh solution of 10% neutral buffered formalin (~4% aqueous solution of formaldehyde or paraformaldehyde) can be used with a volume at least 20 times that of the specimen.
There are other fixatives that are used for paraffin histology. A fixative should be selected to ensure optimal preservation and demonstration of a particular tissue element or histo-technique. Please call the histology lab if you have any questions about which fixative to use for your work.
As a general rule, it is not recommend that laboratories purchase bulk formaldehyde and make up their own fixatives. It is suggested that fixatives be purchased premade and in small enough quantities to ensure the best preservation of tissue specimens.
Please note: The United States Occupational Safety & Health Administration considers formaldehyde a carcinogen. All containers with a formaldehyde concentration greater than 1% are required to be appropriately labeled. If your lab plans to make up Bouin's fixative please be aware that Picric Acid is potentially explosive under certain conditions.
For the best results, tissue for frozen section histology should not be fixed in a chemical fixative. Tissue to be frozen should be placed in a mold and surrounded by a cryoprotectant (e.g. OCT) before being snap frozen. For help with freezing technique, please contact the histology lab. Tissue should be frozen as soon after harvesting as possible to prevent the detrimental effects of autolysis. Frozen sections can be cut on very small pieces of tissue. Care should be taken to not make tissue pieces too large, or they may freeze too slowly, causing ice crystal formation, or the development of cracks.
Hours: 9 am - 5 pm, Monday - Friday
Location: 955 Main Street, Room 3125
Phone: 829-3108 or 829-3093