Effect of freezing thawing on the expression of mannose-ligand receptors on human spermatozoa: the impact on sperm capacitation and acrosome reaction

The aim of this study was to evaluate the change in the expression of manno se-ligand receptors following a freezing thawing procedure, in order to ass ess its impact on sperm capacitation and acrosome reaction. Twenty semen sa mples were obtained from fertile donors. Sperm samples were divided into tw o equal volumes. One aliquot was cryopreserved and the other aliquot was in cubated at 32 degreesC. After 2 h the frozen sample was thawed and both sam ples were further incubated at 32 degreesC to allow capacitation. Mannose r eceptors were examined following 4 and 22 h of incubation using a mannosyla ted-BSA-FITC probe. The expression of mannose-ligand receptors on the sperm plasma membrane was determined according to the fluorescence pattern: patt ern I represents pre-capacitation, pattern II represents capacitated sperma tozoa and pattern III represents acrosome-reacted spermatozoa. After 4 h in cubation in capacitating medium, the percentages of patterns I, II and III were 90, 7 and 3% for fresh spermatozoa and 89, 8 and 3% for frozen-thawed spermatozoa, respectively (P >0.05). Following 22 h of incubation, the perc entages of patterns I, II and III were 84, 11 and 5 for fresh spermatozoa a nd 83, 11 and 6% for frozen-thawed spermatozoa, respectively (not significa nt at P >0.05). The percentages of patterns II and III in fresh and frozen- thawed spermatozoa were increased by the same magnitude with longer incubat ion in the capacitating conditions. It was concluded that the freezing thaw ing procedure for human spermatozoa does not affect the expression of manno se-ligand receptors and the dynamics of sperm pre-fertilization processes.