Abstract
Summary. Cold-shocking and deep-freezing bull and ram semen caused an influx of sodium to and an efflux of potassium and magnesium from the spermatozoa. The movement of these cations was accentuated when the semen was diluted 1 : 8 in sodium phosphate buffers. Calcium is actively accumulated in the spermatozoa of these two species after cold-shocking. No significant changes in the cation content of human, dog, rabbit or fowl spermatozoa were found after cold-shocking. There was no great disturbance of the cation status of human and fowl spermatozoa, even after deep-freezing. Lecithin prevented calcium accumulation in bull and ram spermatozoa on cold-shocking, and glycerol also had this effect on cold-shocked bull spermatozoa. An egg-yolk-citrate/glycerol-fructose diluent protected bull and ram spermatozoa to a considerable extent from the influx of sodium and the efflux of potassium that occurs after deep-freezing to −79°C.