In my research, I often need to make frozen sections of mouse hearts, but I found that the position of the heart was not constant during the embedding process due to the irregular shape of mice. Therefore, in the process of frozen section, the sections of the heart are inconsistent, and the shape of the heart is also inconsistent. I want to know how you solve this problem. Thanks!
Hi Liu x Xx,
Your question is about using OCT to embed whole heart for cryosectioning. It is technical question in nature. I have been using Fisherbrand™ Disposable Base Molds
https://www.fishersci.ca/shop/products/fisher-scientific-tissue-path-disposable-base-molds-5/p-91758
Here is what I do to prep the organ. I perfuse the organ with buffered saline until there is no visible presence of blood, then cut the base of the heart and place the clean-cut surface at the bottom of the cartridge (apex of the heart facing up) to make sure the surface is flat. All should be very clean w/o any blood present in the chambers and (or) outside; also pericardium is not present at this time. I lift the heart and pour a little of OCT (making layer of OCT at the bottom of the mold/cartridge). This will help to stabilize the organ later on, and additionally when organ is back at the surface it pushes the OCT inside both ventricles. Then I use OCT solution to slowly embed the organ. I usually lower my chair to sit down and watch the flow of the OCT at the level of the sample to restrict any movement of the heart during embedding. Then use dry ice to pre-freeze the sample on flat surface before using liquid nitrogen.
Hope this helps,
Filip