Figure 3

The xScisor. The xScisor is essentially a modified syringe consisting of two reservoirs, one above and one below the plunger, and a cutting blade that contacts the slide surface. The xScisor assembly consists of four parts: an outer syringe barrel that mates with the collet on the instrument head assembly, an inner syringe barrel containing the cutting blade (A) at one end, a plunger, and a plug that seals the plunger to the outer syringe body. The width of the dissected area is controlled by the width of the cutting blade; xScisors have been produced with 100, 200, 400, 800, and 1200 micron blades. To use the xScisor, the upper reservoir is filled with milling solution by repeatedly depressing and withdrawing the plunger (Step 1), and then it is loaded into the collet. The collet rotates the entire xScisor as it lowers it onto the slide surface (Step 2). As the stage is moved, the tissue section is driven into the rotating cutting blade and the plunger is withdrawn at a stage speed dependent rate. This action simultaneously dispenses liquid from the outer ports (B), dissects the tissue, and aspirates the liquid along with the displaced tissue fragments into the inner ports (C). A fully loaded xScisor can dispense up to 70 μl of milling solution; it is not necessary to use it all, only what is required to dissect the desired area. When dissection is complete, the head assembly is raised and the aspirated liquid containing the tissue fragments is collected by depressing the plunger (Step 3). The recovered tissue fragments can be pelleted by centrifugation and excess milling solution removed with a pipet. The xScisor can be either reloaded or discarded to avoid sample cross contamination.