“…The main point to be discussed in the classical cytotoxicity test used in our study is the presence in guinea-pig complement (unheated whole serum) of natural spermatotoxic antibodies, the activity ofwhich is thermolabile (Spooner, 1964;Monastirsky & Fernandez Collazo, 1968 (Voisin, Delaunay & Barber, 1951;Freund, Lipton & Thompson, 1953;Voisin, Toullet & Maurer, 1958;Baum, Bough ton, Mongar & Schild, 1961;Brown, Glynn & Holborow, 1963;Mancini, Monastirsky, Fernandez Collazo, Seiguer & Alonso, 1969;Johnson, 1970). Autoimmune spermagglutination has also been studied as well as cytotoxicity for testicular cells (Chutná & Rychlíková, 1964;Chutná & Pokorná, 1967;Mancini et al, 1969;Johnson, 1970). The responsible antigen or antigens had not, however, been identified and guinea-pig spermatozoa possess at least four autoantigens.…”