Dissection ‘hooks’ and ‘sticks’ are useful for removing fat bodies and other detritus when dissecting, as well as ‘hooking out’ muscle 16, which otherwise causes the brain to lightly pulse. These hooks and sticks are custom-made and electrolytically sharpened. This process involves using a 10 Amp transformer and is one of the most dangerous processes in the lab. Take great care and ask a current lab member for help the first time you attempt this.

Equipment and reagents#

  • Tungsten wire, straight cut, diameter 0.15 mm, length 75 mm (this is in excess of requirement), temper annealed. E.g. Advent W560402 Gi2848
  • Blunt needles in holder. E.g. M917 Disposable LL TW Probe Needles
  • Small syringes,
  • Dissection scissors. E.g. FST 15000-04.
  • KNO3 solution.
  • Platinum filament from the puller. We use old ones that we have flattened out. There is a bag of them under the hood.
  • Located under the fume hood. USE WITH CAUTION.
  • Plyers for crimping.
  • Fine forceps.

Process#

  • Take a fresh tungsten wire, insert into your hollow, blunt needle.
  • Secure in place by ‘crimping’, i.e. compressing the needle metal to hold the tungsten wire firmly in place.
  • Cut the wire to your desired working length. Typically this will be about 1.5 cm of straight wire, before curving.
  • Fix the needle holder onto your syringe.
  • With the plyers or a pair of forceps curve your wire as desired. This will be a large curve.
  • Go to the fume hood. Make sure the transformer is unplugged, with the power cable detached. Assemble your workspace.
    • Have your KNO3 solution in a Falcon tube, in a tub rack. Make sure the fluid level is topped up to be very high. You can top this up with DI water to achieve a high level. You DO NOT want to be reaching into the tube later.
    • Open the Falcon tube and place your platinum strip over its lip, bent over the edge. Fix in place using one of the bronze clips attached to the transformer. It does not matter if you use the cathode or anode. The platinum should touch the fluid.
    • Grab your needle from the metal with the other crocodile clip. Make sure it is secure, and not under tension or badly angles, such that it might snap off. Hold from the plastic syringe.
    • Pug the transformer into the lower break-switched power inlet on the left side of the fume hood.
    • Keep your non-dominant hand behind you back before you turn the transformer on. This help prevent you from touching something you should not, and connecting an electric circuit that runs through your heart. Use your free dominant hand to manipulate your implement inside of the fume hood.
    • With your free hand, holding the syringe, toggle the transformer on.
  • Take your implement by the syringe and dip the tungsten wire into the solution. It should fizz. Dip repeatedly in order to taper your wire. Dunk for a longer period if you want to reduce the diameter more uniformly. You may want to dip continually for a few minutes.
  • Take your implement to the microscope. For a hook, bend into a tight hook on an axis orthogonal to the curve of your filament using your fine forceps. When used, this hook stick out to the side, rather than being straight in-line with you, which can be more useful for hooking things. If there is an ultrathin taper, remove it by cutting with the dissection scissors.
Backward Mass flow controller (MFC) MP-225 Forward