I'm not sure why I'm getting a lot of non-specific staining from a rabbit secondary only control DAB stain. It looks like the pattern of staining is picking up blood vessels from my guess.

I quench using 1.5% H2O2 diluted in MeOH for 30 mins followed by permeabilization and blocking with 10% horse serum and 3% triton. Overnight incubation of antibody in 2% horse serum and 3% triton followed by incubation of secondary antibody for an hour and then ABC solution for 30min. All of these steps include 3x 5min washes in PBS in-between.

I perfuse the mice with PBS and then 4% PFA followed by incubation of PFA overnight. 30% sucrose is added to cryoprotect the brains.

I'm not sure if this is in artifact from the perfusions or if something is going wrong during the staining itself. Any help would be appreciative!!