Posted 12 October 2012 - 09:34 AM
Hi there, very nice cartoon you've got there but I would use two nice pairs of forceps each time I dissect the zebrafish brain out. The techniques are a little different between fixed vs unfixed whole head/brain, but generally the fixed tissue is more rigid and 'hard' , thus requiring slightly more force when dissecting out the brain. For unfixed head, I would use one pair of forceps for support i.e. to hold the head on an upright position as shown in the cartoon. You can choose to pierce the forceps through the eyes on both sides for better support/grip. WIth the other pair of forceps, gently remove the scales or 'shell' at the top of the head starting from the base/posterior. It's a very hard piece but once it comes off, you should see the dorsal part of the brain almost immediately. Be careful no to pierce through this shell or you would damage the dorsal part of the brain i.e. the midbrain and hindbrain region. This for me is the most challenging part of the process but it becomes a routine after a few practice rounds. The rest of the steps basically involves using a small pair of dissection scissors to cut/detach the optic nerves from the brain - this will need to be done very carefully to avoid damaging the telencephalon. Once done, use the forceps in a closed position to gently 'scoop' the brain from the bottom in a stepwise manner releasing the brain as your forceps move forward. Once you are midway through, you will notice that the brain will start to 'float - out' from the head and a little wiggle with the forceps will release the brain. Just remember to not stretch or compress any part of the brain tissue whilst dissecting.
Hope this helps!