Abstract:The aqueous two-phase system of 6.2% Dextmn T500 and 6.2% PEG 3350 was used to purify the plasma membrane of isolated sperm cells from Zea mays L. The results from examination of the marker enzymes indicated that the sperm plasma membrane had a high affinity for the PEGrich upper phase, whereas mitochondria of sperm cells prefer the Dextran-rich lower phase. The purified plasma membrane by twice partitioning was morphologically identified with the aid of phosphotungstic acid-chromic acid staining. Electron microscopy showed that more than 90% of the plasma membrane spherical vesicles were stained, which was coincident with the marker analysis.