An improved nozzle system for a flow cytometer have been invented for a high efficiency orientation and sorting process of a flat sample and dedicates items such as equine or bovine sperm cells. This improved nozzle system comprises a nozzle (16) with a novel interior surface geometry that can both gently accelerate the cells and can include an elliptical-like, single torsional interior surface element within (c) the nozzle, i.e., a single torsional orientation nozzle (6). The elliptical-like, single torsional interior surface element (e.g.) (8, 9, 10) may have a laminar flow surface and may produce the simplest flow path for applying minimal forces which act in either an accelerative nature or orienting hydrodynamic forces, namely, the single torsional orientation forces, to orient a flat sample (16) such as animal sperm cells into a proper direction for an analyzing and efficiently sorting process in clinical use, for research and for the animal insemination industry.
