These days all seem to run together when all you work on is Rat and mouse tissues. The odd thing is you get use to it pretty quickly. There are so many ways to process tissues that after dealing with them in great quantity, it seems like almost total recall is inevitable. Sometimes the processes for one set of tissues for a particular study just do not work for another. In this case one must try new-made up protocols until you find something that works. Usually the tissues of Rat and mouse are so similar that they can be substituted for one another. For certain tissues such as bone and eyes, that may or may not be the case. Sometimes there are cases where the client prefers a particular protocol and can provide that for you. I have seen protocols that I believe were passed down from generation to generation, so to speak, that were used originally for hand processing or an autotechnicon. The process was tried and true for those set circumstances once and never modified or tested again afterwords. The client may vehemently insist on using their protocol even when confronted with evidence that another protocol works better. In these times I just try to put myself in their shoes and see from their point of view. In most cases their protocol needs only minor modifications to an already set up protocol in use. There was one time that a researcher would not change until the new process was proven with control tissues processed, cut and stained for review. The old process was 23 hours long for tissues 1cm x 1cm. So here are the processing protocols that we use for all of our mouse and rat tissue, they may help you through your project. Just as a heads up, the machine we use is a new TBS ATP-120. This is a new machine with all the bells and whistles. Prior to this we ran the same protocols on a shandon hypercenter XP with almost exact results. All the protocols are in PDF format and may be downloaded and printed.