When female mice are injected with a specific peptide from the ZP3 protein, their immune systems produce antibodies that target the native ZP3 protein, indicating that B cells in these mice do not recognize ZP3 as self and may be routinely activated by it.

When female mice were given a piece of a protein found in their ovaries, their immune systems made antibodies against the whole protein—even though it’s their own body’s material. This means their immune system didn’t treat it as 'self' and ignored it, as it should, but instead reacted to it like a threat.