I'm not sure if I understood the question correctly ("in Ms on Ms"). I suspect you want to dye or block tissues of mice with mouse antibodies. In general, the antibody that detects the target epitope should not originate from the same species in which the epitope is to be examined. This means, you should not use a mouse antibody to stain mouse tissue. Mouse IgG should not block epitopes on mouse tissue (except from 'autoimmune' reaction).