Some antigenic properties of mammalian spermatozoa

Methods of testing sera for precipitins against seminal proteins, and for spermatozoal agglutinins are described. The influence of various factors on agglutination of rabbit and guinea-pig spermatozoa in hanging drop preparations has been investigated. In diluted normal sera agglutination of spermatozoa by their tails occurred rarely, and then only in low serum dilutions. In the sera of immunized animals tail agglutination commenced within 10 sec., and titres could be read after 20 min. Altering the pH of the diluent below 7·0, or above 8·1, reduced the serum titres. Washed spermatozoa from semen or from the epididymis were agglutinated to higher serum titres than unwashed spermatozoa from the same specimens. A fourfold increase in the con­centration of unwashed rabbit spermatozoa, and an eightfold increase in the concentration of washed rabbit spermatozoa halved the serum titre. Additions of complement did not, in the proportions used, alter the agglutination titres of antisera or the motility of the spermatozoa. The agglutination of rabbit spermatozoa is inhibited by fluid from the vagina. It can be reversed by mechanical means, or by addition of fresh spermatozoa in excess. With guinea-pig spermatozoa disagglutination has been achieved by mechanical methods only. Mixed agglutinates of spermatozoa of different species can be produced by antisera which agglutinate them separately.