How long can the tissue (our sample is rat brain hemispheres) sit (post-perfusion) in the hydrogel solution prior to beginning the hydrogel tissue embedding process. Doing a handful of brains at once isn't an issue, but once we ramp up to full projects, 50+ animals at a time, there is going to be a workflow issue that we are going to have to manage. Is it best to let the sample sit in the hydrogel solution or should we transfer it to something else if it is going to sit for 4 weeks prior to embedding? Is it better to do a traditional perfusion (4% PAF) and then let the sample sit in 4% PAF until we are ready to begin hydrogel embedding? Other thoughts/options/suggestions greatly appreciated.