Module 5: Dissection Protocol
-
- May vary based on site capabilities and/or capabilities of the autopsy technician and research coordinator
- Some sites may have one coordinator performing the entire dissection procedure, at any time of the day
- Coordinator must delicately balance keeping PMI in mind and working quicky, with careful attention to detail at all steps
- If site only does brain donations during regular business hours, adjust steps accordingly, but other team members should be encouraged to help in the lab workflow
- Fully Supported Site
- Brain donation programs with access to -80C freezers and dry ice in the workplace, equipment and supplies listed in Pre-donation procedures section, as well as dedicated autopsy technician and research coordinator to help with brain dissections
- It is also extremely useful to have a computer connected to the internet in the lab space, in case of need to look up brain regions or structures for understanding and/or confirmation
Once brain and biofluids are brought to the lab, follow the link below for the UCI ADRC Brain Dissection protocol
As mentioned previously in the Pre-donation procedures section, universal precautions should be followed, and proper PPE should be worn at all times when handling fresh brain tissue and biofluids
-
- Steps should be completed in a biosafety cabinet or enclosed structure whenever possible to mitigate exposure of potentially infectious agents that can be in the brain environment
All steps in above protocol mentioning names of researchers are referring to pre-arranged tissue requests for the researchers’ specific projects. Brain donation programs should aim to be collaborative as much as possible, within reason considering PMI of brains for fresh tissue requests
-
- Coronally sectioning the fresh/to-be-frozen tissue allows for better access to more brain subregions for future tissue requests to researchers
- It is helpful to place the fresh coronal sections in plastic heat seal bags in proper anatomic position before placing on frozen metal plates, so that they freeze flat and not distorted in any way
- Be mindful of touching too many other things in the lab with contaminated gloves. You can periodically spray your gloves with Envirocide or other disinfectant and wipe off the excess with a clean paper towel. You can then rinse your gloves with de-ionized (DI) water and dry again with a clean paper towel before touching the brain tissue
- You should also rinse off your gloves with DI water after your gloves have been covered in fixative before touching the dissected hemisphere
- You can also change to new gloves if felt more efficient
- Be sure to note all relevant information, such as fixation and freezing times, any notable pathology (take pictures if possible), how many coronal sections were produced, from what coronals were regions dissected out, how many biofluid aliquots, etc.
For minimally supported sites with no access to -80C freezers or dry ice, the brain must be fixed whole
- Full brain fix protocol:
- Fix the entire brain by threading a piece of post-mortem thread (longer than the diameter of the specimen bucket) underneath the vertebral-basilar artery to suspend the brain in a closed 172oz specimen bucket filled with at least 4L of 10% Formalin
- This ensures that the brain does not rest on the bottom of the bucket and warp its morphology
- A thin hairnet can also be used to suspend the brain, secured by the cap of the bucket
For sites with dry ice and ultra-cold capabilities, but coordinator or autopsy technician is not yet trained on dissection, fixed and frozen tissue can still be banked
- If autopsy technician and research coordinator do not feel comfortable coronally sectioning fresh tissue, they may bisect the brain and freeze one hemisphere and fix the other
- Frozen hemisphere can be coronally sectioned at a later time by placing in -20C freezer overnight and sectioning with long autopsy knife
- Follow step 7 on the above Dissection Protocol link for bisection of hemispheres
Advanced Dissection Procedure, Fully Supported Site
-
- Other brain donation programs have more involved protocols that are aimed to result in thinner (~4mm), more uniform coronal sections that allow for more brain sub regions to be accessible and identifiable.
- This particular protocol also involves flash freezing the brain coronals in dry ice and 2-methylbutane, between coated metal plates, resulting in very flat and thin coronal sections
- Thinner frozen coronal sections are more likely to break; it can be beneficial to store these coronal sections in vacuum seal bags, to help keep the orientation of the coronal if it breaks into pieces
If you have any additional questions regarding dissection protocols, please refer to the Contact us page