Getting started

What size should the specimen be?

All specimens should be thin (1- 5 mm) and have uniform thickness. For larger specimens, please cut them in half or in smaller pieces according to the desired orientation or contact the Core for specific instructions.

What solution should I put my specimen in?

All samples that are brought to the core should be properly fixed (see Tissue Fixation section) and put in a container with 70% ETOH.

How do I label my samples and/or cassettes?

All samples must be clearly labelled with the sample name on the tube. In addition, an excel spreadsheet (downloaded in iLab) with each of the sample names must accompany each work order. Label all tubes or cassettes using a lead pencil or pen specifically designed for histology labelling. DO NOT USE A SHARPIE OF ANY KIND!

Fixation is the first stage of preparing tissue or cells in histopathology. It functions to preserve the tissue from decay due to autolysis. Fixation should be done as soon as possible after the tissue is removed from the host. Animals can either be perfused with a fixative or the tissue can be immersed in a fixative solution after dissection.

What type of fixative do I use?

For paraffin embedded tissue, 10% buffered formalin or 4% paraformaldehyde are most commonly used.

How much fixative do I use?

Ensure that the fixative volume is at least 20-50 times greater than the tissue volume.

How long do I fix my sample for?

This will depend on the size of the sample. Usually 48 to 72 hours should be sufficient. Please contact the Core if you are unsure of fixation times for your samples. Insufficient fixation is the main culprit of artifacts and inaccuracy in the morphology. Fix samples at room temperature and transfer them to 70% ethanol before bringing them to the Core.

How do I prepare cells for fixation?

Pellet the cell suspension in an Eppendorf tube at low speed in a microcentrifuge. Carefully remove the supernatant and add 10% formalin and fix for 4 to 24 hours at room temperature. Transfer to 70% ethanol before bringing it to the Core.