Density gradient centrifugation and glass wool filtration of semen remove spermatozoa with damaged chromatin structure

The ability of double-layered density gradient centrifugation (DGC) or glas s wool filtration (GWF) of semen to remove spermatozoa with damaged chromat in structure was assessed by the flow cytometric sperm chromatin structure assay (SCSA), which measures the susceptibility to sperm nuclear denaturati on in situ. Ejaculates from 26 men attending a university-affiliated assist ed reproduction laboratory were processed by DGC and GWF. Unprocessed, DGC- and GWF-processed specimens were assessed by the SCSA and by conventional semen parameters. Changes in chromatin structure were compared with convent ional semen parameters. Both sperm preparation techniques yielded sperm sus pensions with improved sperm chromatin structure as well as motility (%), f orward progression (1-4) and viability (%), DGC ras superior to GWF in the efficiency of recovering motile, morphologically normal, mature sperm suspe nsions. However, GWF produced improved chromatin integrity (SD alpha(t)) an d viability. Moderate correlations between SCSA and conventional sperm para meters were observed. Nevertheless, the SCSA provides additional informatio n about the biochemical integrity of sperm DNA and may be used in future st udies to provide insight into assisted reproduction technology outcomes not ;explained by conventional sperm parameters.