STUDIES ON THE ANTIGENIC STRUCTURE OF SOME MAMMALIAN SPERMATOZOA.

1. A method has been described for separation of heads and tails of mammalian spermatozoa. 2. By means of absorption technique applied to homologous spermatozoal sera, head-specific and tail-specific antigens could be demonstrated. Both are heat-labile. 3. A heat-stable antigen was found to be common to both heads and tails. This substance is species-specific. 4. Antibodies against the head- and tail-specific antigens led to two different types of agglutination as shown by the slide method. 5. Using heterologous antisera against spermatozoa three different cross-reacting antigens could be observed, two in the heads, one in the tails. 6. One of the head-antigens is not active in the native cell; it comes to action only after breaking the cell. Antibodies against this substance were not found in antisera against native bull spermatozoa but were formed when vibrated spermatozoa or heads were injected into rabbits. 7. The cross-reactions can be removed from an antiserum leaving the head- as well as the tail-specific reaction intact.