I recently attempted my first DAB staining in the mouse brain. I used 40um thick sections from frozen brains and we used a "free floating" method. Some protocols advised to use 0.3% H2O2/PBS to quench endogenous peroxidase and others suggested 0.3% H2O2/100% methanol. So I used both. What I noticed is that those that were treated with the methanol solution appeared very "bubbly" whereas those in the PBS treatment were clear and neurons and structures were clearly visible.
Was my experience with the methanol due to some technical error on my part or is this a normal occurance for this tissue and I should use PBS instead ?