IDENTIFICATION OF 2 HUMAN SPERM POPULATIONS USING FLOW AND IMAGE CYTOMETRY

Flow cytometric studies of human sperm from fertile men display a cons tant and characteristic bimodal nonartifactual DNA pattern confirming the existence of two distinct populations. The main population is repr esented by a peak followed by a shoulder (''marginal population''). Th e appearance of this marginal population fluctuates with either freezi ng and thawing or with Percoll gradient centrifugation. We have analyz ed both the main and marginal sperm populations by flow cytometry afte r cell sorting, laser scanning cytometry, light microscopic evaluation , and their sensitivity to DNase digestion. We have observed that the marginal population detected in fertile men represents a sperm group a ltered in the nuclear condensation, yielding unstable chromatin which appears more stainable with propidium iodide. (C) 1994 Wiley-Liss, Inc .