For Microdissection of Frozen Brain Sections.
The kit is available in 2 different sets: Complete with either 3 punches or 5 come complete with spring loaded nylon expellers, and a convenient handle, facilitates the "Palkovits Punch" technique of dissecting out specific brain nuclei for neurochemistry.
The nuclei are punched from frozen brain sections on glass slides, and expelled into the reagents. The spring-loaded expellers avoid risk of contamination that might be caused by expelling with breath.
Each punch has an electro polished sharp end for smooth cuts and minimal tissue adhesion. Punch sizes are 0.25, 0.50, 0.75, 1.0, 1.25, 1.50, 1.75 and 2.00 (± 5%, slight variation due to electro polish etching to sharpen). The smaller tubes are reinforced by an outer layer of concentric tubing except at the tip.
Replacement punches available individually.
Applications
The Brain Punch Kit is a set of electropolished and sharpened punches for the Palkovit's punch technique. Note that the smaller punches are reinforced, as these can tend to bend under the force of the punching action. The set includes a handle and 5 sizes of punches. Sizes are shown in the table below. Each punch consists of the stainless steel punch column, the holder body, and a button which operates a spring loaded expeller to force the micro dot of tissue from the punch.
Select the punch to be used and install it in the handle so that the black body holder on the punch is flush with the lower surface of the handle. Tighten the locking screw. If the punch body holder extends below the handles bottom surface, the action of the expeller may be blocked. Check that the expeller end can be seen when the button is pressed, and then proceed.
Method
To prevent deterioration of the proteins, the tissue must be kept frozen as much as possible. The brain or other tissue to be punched is dissected from the anesthetized animal and dropped into liquid nitrogen. The frozen specimen is mounted on a sectioning pedestal, placed in a cryostat, and allowed to equilibrate to the cryostat temperature. At this time, glass slides for collection of the sections are also placed in the cryostat to equilibrate to the temperature.
The specimen must be adjusted to the correct plane of section, taking preliminary sections to check the angle, and then the critical sections from the desired region are collected.
Thick (~200 micron) are taken and placed on the prechilled glass slides. The frozen slices will lie on the frozen glass without adhering, so care must be taken not to spill them. When the slide is full, press a finger against the bottom of the slide to cause the tissue to partially thaw into contact with the slide, and refreeze promptly in the cryostat.
Remove the slides from the cryostat and place on a cold plate or petri dish chilled with dry ice. Select the punch needed, position the tip over the area to be removed, and press down. The dot of tissue, whose volume can be calculated, will pull away from glass slide and stay in the punch. Press the spring loaded button on top of each punch to expel the tissue into the collection media.