Flow cytometry nozzle for high efficiency cell sorting

A nozzle comprising a body having a first interior zone and a second interior zone, said first and second zones being separated by a transition zone, wherein essentially all cross-sections of said first and second zones and said transition zone are in the shape of an ellipse having a long axis and a short axis, wherein said first zone comprises a mouth and is tapered from said mouth to said transition zone such that the cross-sectional area of said transition zone is less than that of the mouth and the ratio of the long axis to the short axis increases as the cross-sectional area of the first zone decreases from the mouth to the transition zone, wherein said second zone is downwardly tapered from said transition zone to an exit orifice having a cross-sectional area less than that of the transition zone and the ratio of the lone axis to the short axis decreases from the transition zone to a point within the second zone where said lone and short axes are equal and thereafter the ratio of the long axis to short axis increases and the lone axis is at approximately 90.degree. to the lone axis in both of said mouth and said transition zone, and wherein the long axis in said exit orifice is at approximately 90.degree. to the long axes in both of said mouth and said transition zone.