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Human Sperm Produced In the Laboratory
duh P3rf3ss3r writes "The BBC is carrying a report from a team of researchers at Newcastle University who claim to have developed a the first 'artificial' human sperm from stem cells. The research, reported in the journal Stem Cells and Development, involved selecting meristematic germ cells from a human embryonic stem cell culture and inducing meiosis, thus producing a haploid gamete. The authors claim that the resulting sperm are fully formed, mature, human sperm cells but the announcement has been greeted with mixed reaction from colleagues who claim the procedure is ethically questionable and that the gametes produced are of inferior levels of maturation."
And, on a chilling (for me) twist, if they took stem cells from a woman, they could generate some sperm for her, thereby allowing her to impregnate herself .
Sperm doesn't have pairs of chromesomes, it has only one. But you're right, if you make sperm from female stem cells it could only have an X chromesome, never a Y chromesome, so you'd only get female offspring.
The only inherent loss of genetic diversity would be the Y chromesome, which doesn't have much genetic information on it anyway. The wiki page on the Y chromesome points out that "the human Y chromosome itself contains only 78 working genes, compared to close to 1500 working genes on the X chromosome" and none of the 78 are "vital." For women anyway for obvious reasons.
As long as the female that the sperm are derived from isn't closely related to the female that produces the egg, it wouldn't seem like there would be diversity loss.