Abstract
The plasma membranes of ram spermatozoa were disrupted in a hypotonic EDTA medium and isolated by using a 2-phase polymer system of dextran-polyethyleneglycol. The plasma membranes obtained were of a relatively high degree of purity (.apprx. 70%) as judged by EM observations and measurements of the marker enzymes alkaline phosphatase, ATPase and AMPase. The activity of succinate cytochrome C reductase, a marker of mitochondrial membranes, was very low.