Worm Breeder's Gazette 11(4): 7
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The accompanying diagram shows the system which we use to pressurize our microinjection setup. The key feature of this system is the three way ball valve through which pressure at the needle is applied and then rapidly relieved during each injection. Pressure must be off between injections because the high flow associated with optimal injections will float animals off the pad before the needle can be inserted. It may be possible to adapt your current system to include such a valve, or to construct a similar system with other parts. [See Figure 1] 1) Leitz microinstrument collar (part no. 520145). Holds the injection needle. 2) 3/32' outside diameter (1/32' I.D.) Tygon tubing. This tubing, once stretched, will fit snugly down the opening in the back of the microinstrument collar. This junction is taped with electrical tape. The tape keeps this joint from getting worked loose during the frequent handling of the microtool collar. The tape should not be necessary to make the pressure seal. 3) 21g metal tube (cut off of a syringe needle). Fitted halfway within the 3/32' tubing, the protruding portion is inserted into the 1/16' tubing and serves as a connecter. This connection is also wrapped with electrical tape. 4) 1/16' polyethylene tubing (rigid plastic or nylon tubing works best with the Swagelok adapters). Note; if you plan to HF treat your needles (Worm Breeders Gazette 11-1:18), then this tubing should be long enough to reach a nearby dissecting scope. S) Swagelok reducer (part no. B-100-R-2). Connects the 1/16' tubing to the Swagelok 1/8 connector which comes with the three way valve. 6) Swagelok three way ball valve (part no. B-41XS2). Should be mounted or clamped in place. This valve is used during each injection to apply pressure at the needle. It should be placed within easy reach but should not be on the vibration free table. 7) Swagelok male connector (part no. B-100-1-4). This connector threads into the 1/4 NPT female socket of the STREET TEE. 8) CAJON STREET TEE connector (part no. B-4-ST). Male end threads into the pressure regulator. Female ends accept the tubing connector and the pressure release valve. 9) Swagelok toggle operated shut off valve (B-1GM4-S4). This valve opens the system to allow a quick release of pressure. This is necessary when using the pressure regulator to make downward adjustments in pressure, for example if there is too much flow at the needle. 10) Pressure regulator. Must have a 1/4 NPT Female thread in order to accept the STREET TEE described above. Allows the pressure to be increased or decreased. Pressures required for adequate flow range from 10- to 100-lbs/sq.in. depending on the needle; higher pressures tend to blow connections or to propel the needle out of the holder at high velocity. 11) Nitrogen tank. Should be positioned so that the regulator handle can be reached easily without getting up during injection. Happy injecting!!