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Colorado State University says it can reliably sort sperm with X chromosomes
from those with Y chromosomes, allowing the sex of mammalian offspring born by
artificial insemination to be chosen. The key to the process is a dye that
stains sperm cells slightly different colours depending on which sex chromosome
they have. The dyed sperm are given a small charge and then blown past a laser
that detects the colour changes. An electrostatic plate deflects X-bearing sperm
into one container and Y-bearing sperm into another (WO 99/33956). The
university says it can sort bovine sperm at the rate of at least a thousand a
second. The technique can be applied to human sperm.