I have seen biologists use mouse grown primary antibodies in mouse tissue, and they've told me that if the blood is perfused well then there is no problem with this method. How does the secondary antibody (anti mouse) not stick everywhere on all the mouse antigens in the tissue?
Clarification: I understand that the secondary antibody is very specific to all mouse "class" primary antibodies. Can I ask then why using a secondary mouse antibody does not recognize background antibodies in the tissue, the ones that the mouse produced for itself naturally before I added any of my primary antibody? Are the existing primary antibody levels already present in the mouse much lower than the levels of the primary antibody I am adding?