Abstract
Modification of a Coulter EPICS V orthogonal laser‐based flow cytometer/cell sorter allows resolution of X and Y mammalian sperm populations based on DNA content. The modification consists of beveling the sample injection tube situated in the flow chamber, adding a second fluorescence detector directly forward along the laser beam axis, and routing the collected fluorescence through an optical fiber bundle to one of the existing photomultiplier tubes. The X and Y chromosome‐bearing spermatozoa from the bull, boar, and ram can be resolved using this system.