Comparative biochemistry of mammalian epididymal plasma.

1. A comparison has been made of the chemical composition of epididymal plasma from the cauda epididymidis of nine mammalian species. 2. Results have shown that epididymal plasma contains low concentrations of inorganic ions and high levels of several unusual organic constituents, among which may be mentioned glycerylphosphorylcholine, hypotaurine, carnitine and several glycosidases and phosphatases. 3. The influence of this milieu on the motility and survival of spermatozoa is discussed.