Abstract: A method to make an immuno-differentiation of bovine sperm cells using monoclonal antibodies against male specific antigen, 17.18 kDa protein, associated to proteins of the classic pathway complement system is described. Monoclonal antibodies directed towards a gender-specific protein associated to the complement, provoke cellular rupture. For this methodology to be useful, an elimination of the alternative pathway of the complement is necessary. The sperm cells are then put in contact with a monoclonal antibody specifically for the gender-marking protein. Thus, the classic pathway complement system causes selected rupture of the marked sperm cells. The sperm cells of the treated semen are then ready to be used in artificial insemination, cryo-preservation or “in vitro” fertilization.