SURVIVAL AT 20-DEGREES-C AND CRYOPRESERVATION OF ISOLATED SPERM CELLSFROM ZEA-MAYS POLLEN GRAINS

The survival of isolated sperm cells from maize pollen grains at 20-de grees-C and their cryopreservation were studied by means of the fluoro chromatic reaction (FCR) test. An osmotic pressure of 500 mOsmol, a pH of 7 adjusted with MOPS buffer, and the ten-fold dilution of Brewback er and Kwack salts enabled isolated sperm cells to survive for a maxim um of 35 h at 20-degrees-C. The addition of 3 mM of calcium chloride o r 0.1% glucose also slightly improved survival. The addition of 1% glu tamine gave the best percentage of FCR-positive cells at 20 h. The add ition of all of these substances in a unique medium provoked the forma tion of sperm-cell aggregates that were FCR positive. With respect to cryopreservaton, 70% of the isolated sperm cells remained FCR positive after freezing at -80-degrees-C and quick thawing at 37-degrees-C in the selected survival medium.