“….Human ZP antigens are believed to consist of two components; one is antigen(s) proper to human ZP and the other is antigen(s) shared by human and porcine ZPS. 24 If antibodies detected by the PHAR test are directed to the common antigents), then the questions arise of whether these antibodies can cause infertility at such low titer, and, if not, whether the serum giving a positive PHAR possesses autoantibodies against antigen(s) proper to human ZP. The answer to the former question seems to be no, because murine monoclonal antibodies against a common antigen of porcine and human ZPs are required at high titers to inhibit sperm penetration across the human ZP in vitro as described elsewhere.F' and so the answer to the second question is that autoantibodies against the antigen(s) proper to human ZP probably coexist with those reacting with the common antigen(s).…”