Bio-art is the bridge between science and art that highlights the beauty within the intricate workings of our bodies and all nature. There is such a large variety of bio-art; some more extreme than others. For example, Eduardo Kac commissioned a French lab to create a fluorescent green rabbit in the name of transgenic art. For an even more shocking and interesting story, I would suggest looking into Stelarcs project: Making Art of the Human Body. Making art out of body tissue is what we like to do in the Kennedy histology facility, granted in a much more tame way than these examples! However I would argue the result is much more visually beautiful than an ear structure poking out of a humans forearm! Not only is histology paramount for research and answering important scientific questions, but there really is a hidden beauty in nature even down to the cellular level that we aim to unveil through histological processing and staining.
Now for the nitty gritty. As you can imagine our lab works with all types of tissue samples from lots of different research groups throughout Oxford University and further afield. But the process for most tissues is widely the same. We’ve put together a step-by-step guide on how we create these beautiful images from research tissues.
Step one - Formalin fixation
Storing the tissue in formalin as soon as possible after dissection prevents decay and preserves the specimen for evaluation later. The formalin binds with proteins and parts of the cells by forming cross-links, and these protect the cell structure and prevents shrinkage. Once the samples have been fixed for 48 hours, they are stored in 70% ethanol until they are ready to be further processed.
The samples are encased in labelled cassettes and placed in the tissue processor. Inside the machine they are dehydrated with alcohol which removes all the water. Next, the alcohol is removed and replaced with xylene. This process is called clearing.
The samples are infiltrated with molten wax, making them hard and easier to cut into thin slices.
They are moved to the embedding station. They are encased into blocks using moulds and left to harden in the fridge. Once set, they can be stored at room temperature and are ready to be sectioned.
The histologist uses a machine called a microtome to cut very precise and very thin sections that are about 20 times thinner than a strand of hair! The section is floated on a water bath at 60 degrees to flatten it. It can then be transferred straight from the water bath onto a glass slide and baked at 65 degrees. This ensures the sample has attached to the slide and the remaining wax has melted.
Most cells would appear clear and colourless under a microscope, so the baked slides are stained with special dyes that attach to different molecules. Staining ensures that different structures stand out from one another in the sample which helps analysis and adds to the beauty of the sample. This is sometimes done in the staining machine and sometimes manually.
A thin piece of glass called a cover slip is placed over the slides, which are then baked again.
The samples are now ready to be analysed under the microscope by researchers. They may be looking for abnormalities that might indicate disease or they may be looking to get a better understanding of the structure and cells within tissues.
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9 September 2021
Earlier this year, the histology team at The Kennedy Institute were thrilled to receive an enquiry like no other. We are used to processing and sectioning a wide variety of tissues for Oxford university researchers as well as other British and European institutions; however, we never expected to deal with chicken breast and beef steak from Sainsburys!