Effects of Some Phosphatidyl Compounds on Boar Spermatozoa Following Cold Shock or Slow Cooling

A.R.C Unit of Reproductive Physiology and Biochemistry, 307 Huntingdon Road, Cambridge CB3 0JQ (Received 9th October 1974) Rapid cooling of the spermatozoa of most mammalian species leads to irreversible decrease in motility and metabolism (Milovanov, 1934; Chang & Walton, 1940), leakage of intracellular proteins and enzymes (Mann & Lutwak-Mann, 1955), increase in the proportion of differentially stained cells (Easley, Mayer & Bogart, 1942) and changes in cellular cation concentrations (Blackshaw & Salisbury, 1957). These effects could all result from changes in permeability which suggests that the cell membrane is the principal target of injury. The visible disruption of membranes, particularly in the acrosomal region (Hancock, 1952), supports this hypothesis. Phospholipids are of major importance in membrane structure and ram, bull and boar spermatozoa are known to release phospholipid into the surrounding medium on cold shock and freezing (Darin-Bennett, Poulos & White, 1973). Various compounds, most notably milk and egg yolk,